For fishing in the cambridge area,try these two shops....
The carp cabin,london rd ind est,pampisford.This shop is located inside the country store there and is a veritable aladins cave.I used to pop in and buy something,everytime i was in the area.The old boy incharge is ever so friendly and certainly knows his onions.
The other shop to try is is farringtons,fery lane,chesterton,cambridge.I dont know a great deal about this place,having only visited it once,when i was delivering packages to it.It`s well stocked and the owner and son seemed friendly enough.
Also,there is a chap who does guiding on the waterways that run through the heart of cambridge.Unfortunately i havent got his details but one of the chaps on this site might know who i`m talking about or one of the tackle shops i have mentioned might know of him.