Finally fully solved!
Bear in mind throughout that ultimately our aim is to decode the block of symbols which is supposed to be an 'itinerary' for the next time the two characters in the story meet up. This means it will most likely work out to be a list with some meaning to the pair of them. Let's now work out what that might be...
First notice that the list of 'recommendations'...
...provides a set of clues (via character names, locations and plot points) to books that have a number in the title:
33 Violet Sepotho (the whole series is good!) = THE NO. 1 LADIES’ DETECTIVE AGENCY
34 Barad-dûr and Orthanc = THE TWO TOWERS
35 Candace and Toby = MISSING AT 17
37 Psammead = FIVE CHILDREN AND IT
38 Opo, Spray, Doris, Buzz and Tuffy = NINE TRUE DOLPHIN STORIES
40 Kirsten Raymonde = STATION ELEVEN
41 Solomon Northup = TWELVE YEARS A SLAVE
42 Meg and Minnie = TEN
44 Sam Deker = THE 34TH DEGREE
45 Harry August = THE FIRST FIFTEEN LIVES OF HARRY AUGUST
46 Dr. Siri Phaiboun = THIRTY-THREE TEETH
58 Kara Spencer, Flowers not Space = TWENTY-SIX ROSES
59 E.L. Pender = TWENTY SEVEN BONES
60 Unnamed Rabbi of Talmudic Legend, 1976 = THE RABBI AND THE TWENTY-NINE WITCHES
61 Natalie sends letters to Dan = 16 WAYS TO BREAK A HEART
62 Rose Gardner (It's the smallest I can find, but I wish it was smaller by half) = TWENTY-EIGHT AND A HALF WISHES
91 Milady de Winter = THE THREE MUSKETEERS
92 Ivor Orr = CATCH-22
94 Tom Holt and the computer simulated Brothers Grimm = SNOW WHITE AND THE SEVEN SAMURAI
95 Shannon Molloy = FOURTEEN
124 Pamphylius and Julius, amongst many others = TWENTY THREE TALES
125 Chi-Yuen Ai-Ling = TAU ZERO
126 Professor William Waterman Sherman = THE TWENTY-ONE BALLOONS
Note also that the numbers indicated as 'rankings' at the start of each row in this list...
...correspond to ASCII codes for symbols:
33 ! 34 " 35 # 37 % 38 & 40 (
41 ) 42 * 44 , 45 - 46 . 58 :
59 ; 60 < 61 = 62 > 91 [ 92 \
94 ^ 95 _ 124 | 125 } 126 ~
What we have here then appears to be...
...some kind of key that can likely be used on the symbol-encoded 'itinerary', where each ASCII symbol corresponding to a book's 'ranking' is equivalent to the number found within the title of the book:
! is 1 " is 2 # is 17 % is 5 & is 9 ( is 11
) is 12 * is 10 , is 34 - is 15 . is 33 : is 26
; is 27 < is 29 = is 16 > is 28 [ is 3 \ is 22
^ is 7 _ is 14 | is 23 } is 0 ~ is 21
Applying this, then, to the encoded itinerary we see that all except one symbol (+) can be translated, resulting in the following (obviously further-encoded) message:
22/10/28/17 + 22/14 + 28/21/10/28/17 + 22/14
28/3/2/29 + 10
14 + 17/5/1/26/2/33
Next, we should note the remark within the puzzle: "it was, basically, 35 or 36 books you asked for"... This means we should...
...interpret the resulting characters using base-36 (references to 'basically' and '36'). In this base the numbers 0-35 are used to encode the digits 0-9 followed by the letters A-Z. This means 'A' is represented by '10', explaining one of the hints:
"My friend lives near Foxton Railway Station, England; and is often inspired by his local road network when setting cyphers and clues."
...since the nearest major UK road to this railway station is the 'A10'.
Applying this newfound knowledge gives us the following translation:
The first line of this clearly forms legitimate words in English - 'MASH ME, SLASH ME' - suggesting this is some kind of instruction to be applied to the rows that follow.
What does this instruction mean?
In my own head (and this may not be the OP's precise intention for their choice of words) 'MASH' implies rearranging, while 'SLASH' implies splitting something into two.
How do we apply it? Well, recall the thus-far unused section: I finally figured out your last puzzle by the way - is the answer
...a rot-13 encoded web address for "https://www.google.co.uk/maps/dir/U/K/C/o/d/e/s". Needless to say, this is not a genuine URL, but instead provides a nudge towards some combination of maps and UK codes. With the friend working at the post office (Hint 1), this is a definite nod towards UK postcodes.
...each of the lines beneath the instruction appears to be a jumbled-up postcode, judging by their length and the ratio of number:letter characters. This would be fitting, considering that we seek a coded itinerary - a list of locations (through postcodes) would be a perfect fit for what we seek. The question is now how to reorder these jumbles to produce the required postcodes?
A systematic approach that produces valid-looking postcodes is to take first the characters in the odd-numbered positions, then those in the even-numbered positions. This produces the following strings:
CR0+7AA, B70+9LS, NG9+2AR, S2+3TA, M50+3YL, FY1+5AA, and EH12+5QX.
Interpreting the '+' characters as spaces1 yields a set of locations that all have something in common - these are all nearby to TRAM STOPS:
CR0 7AA = Addiscombe Tram Stop, Croydon
B70 9LS = Dudley Street Guns Village Tram Stop, West Bromwich
NG9 2AR = Middle Street Tram Stop, Nottingham
S2 3TA = Arbourthorne Road Tram Stop, Sheffield
M50 3YL = Anchorage Tram Stop, Salford
FY1 5AA = Central Pier Tram Stop, Blackpool
EH12 5QX = Murrayfield Stadium Tram Stop, Edinburgh
In fact, if we exclude the Tyne and Wear Metro system up in Newcastle-upon-Tyne (which is more of a light railway), the seven towns and cities in this list have the only tram networks in the UK - perhaps it would not be farfetched to suggest (what with the travel-related references to 'coach', 'express' and 'track') that the two characters in this scenario are both tram enthusiasts!
1 EDIT: The plus symbols here didn't actually need to be converted into spaces if one of the hints in the puzzle had been interpreted in a specific way. In Google Maps (referenced in the rot-13'd hint), a specific postcode can be targeted by typing it at the end of the URL with a plus symbol in place of the space (e.g. https://www.google.com/maps/place/CR0+7AA).
So what's their plan?
As typical tram enthusiasts, they are planning the Holy Grail of tram enthusiasm: a day in which they tour the UK specifically to ride on every single one of its official tram networks. They will start in Croydon (south London) and work their way up the country, via West Bromwich, Nottingham, Sheffield, Salford and Blackpool (always moving northwards) until finally reaching Edinburgh, approximately 340 miles (550-ish kilometres) from their starting point as the crow flies.
What will they do there? Well, with their final destination being so close to Murrayfield rugby stadium I suggest they will most likely be heading up to watch a match! Though of course, Edinburgh (which is without doubt my favourite city in the world) holds so many other delights too. I hope they make the most of their time up there and explore it properly!