According to wiki-pedia a dormouse is anything from 6 to 19cm long. Will's pet is generally depicted as being on the high side of that, if not larger - perhaps to make sure it's visible in the comic. As a guide, he's about as long (without tail) as someone's forearm which would be extraordinarily large - cat-sized perhaps.
Heatherfield appears to be on a west-facing shoreline and given references to Taranee's brother being a devoted surfer, I'd guess it's somewhere in the West Country which isn't particularly urbanised. (To give an idea, roughly a quarter of England's population live in London, all the south-western counties together contain perhaps a a quarter as many in an area fifteen times as large).
I don't recall ever reading anything by Joan Aiken so I can't comment.
D for Drakensis
You're only young once, but immaturity is forever.
Heatherfield appears to be on a west-facing shoreline and given references to Taranee's brother being a devoted surfer, I'd guess it's somewhere in the West Country which isn't particularly urbanised. (To give an idea, roughly a quarter of England's population live in London, all the south-western counties together contain perhaps a a quarter as many in an area fifteen times as large).
I don't recall ever reading anything by Joan Aiken so I can't comment.
D for Drakensis
You're only young once, but immaturity is forever.