Pre teen fiction book letter exchange

Hi this is my first post so apologies if I get anything wrong.
Just wanted some help finding a book I read when I was a child. It was a fiction book that was a sort of half cartoon illustrations and half writing filled book. I vaguely remember two people writing letters back and forth (maybe penpals?), one letter involving one of them describing how cats are believed to have 9 lives and they were worshipped in Ancient Egypt. The illustrations corresponded pretty well with the writing. The letters would sometimes end with one person adding P.S, P.P.S, P.P.P.S and so on and so forth. One of the letters would describe how they were having trouble sleeping because of the noise outside. Near the end of the book I think they met up and one of them was involved in the rescue of a cat? (Fireman style with a ladder) Not a hundred percent sure as I could just be projecting a similar book's plot onto it. The book that I read had a solid green shiny cover (the giving tree book shade of green), it was a paperback with thin pages, with some cartoon illustration on it, maybe a cat? (not too sure about this either)

It wasn't a complete children's book, it seemed more thicker and more word heavy. It was an a5 sized book. Perhaps a book for 8 year olds?
I've been looking for this book for a really long time so if you could help me a bit that would be amazing!

If not, thanks so much for reading anyway!

Possibly this is Regarding the Trees or some other book from that series?

When were you a child? It might help to know how old the book is.

Sounds like one of the books by Pseudonymous Bosch The Secret Series, the Bad Books

>2 merrystar: Hi sorry for the late reply, for some reason could not find the original post haha. I was born in 1999, but since I have two elder siblings who are about 9 years older than me it could also be a hand me down book. It doesn't look like Regarding the trees book, but I will have a look at the other books in the series too.
Thank you so much for all your help anyway, really appreciate it!! :D

>3 DaddyRobz: Hey! I had a look at Pseudonymous Bosch but the plot doesn't seem to ring any bells, I think the art style is also quite different. Sigh**
Thank you so much for your help though! I really appreciate it :D

PS Longer Letter Later?

touchstone: P.S. Longer Letter Later

>6 paintedlady1709: Unfortunately not. I had a look into the book, the beginning plot premise seems kind of similar but then it kind of diverges off when it goes into more serious topics. I remember the book I read as being really simple, kind of child-like?
Thank you for your help though! :D

>7 merrystar: I had a look at this right before. Unfortunately as I said in the other comment, it doesn't seem to be it, it seems kind of similar but definitely don't remember more serious topics like the father losing his job and leaving the family. It also felt as though the characters I remember were of adult age or older than 12 years old but again I can't be too sure because of my awful memory. Apologies for the spotty memory TvT.
Still thank you so much for trying!!

Long shot, but possibly one of Amy Hest's books, e.g. The Great Green Notebook of Katie Roberts?

>10 beyondthefourthwall: I just had a look at her books but it doesn't seem so... I think the vibe I get from her books is a little more serious formative years kind of stuff. The book I read was very lighthearted, it was more like a back and forth between two casual friends, both adults I believe. Cats were just one part of it, I believe they talked about other really mundane things too, all the illustrations had a very cartoonish feel to it which kinda added to that lighthearted feel of it.

STILLLLL thank you so much for your help! I will now add this book to the list of "can't be" and it's back on the search again. >

BTW update the worshipping scene kinda resembles this cover from this book (of course in black and white and much less detailed) and yes unfortunately this book is also not the book I am looking for...
https://www.penguin.com.au/books/the-bill-the-cat-story-9780399546624