Daventry eh? I might have an aeroplane near by, but that's no use to you!
Leicester is a bit too far. I would say three options from Daventry. Sywell, Coventry and Wellesbourne. Sywell don't do flight training yet so that's out.
Wellesbourne - Wellesbourne Aviation have a modern fleet learning on Robin 200s and the place a good club feel (I learnt there). I understand South Warwicks are okay too but last time I looked you'll be leanring on C152s. PFT seem to do a stable trade on their proven yet aging fleet.
Coventry - Atlantic seem good chaps and know their stuff; I recently converted onto a tailwheel with one of their instructors. Not cheap though. With MATS you have a choice of Cherokee and that's it. AWA are not-for-peofit and have been going for 50-odd years, so if you like that ethic give it a shot. All 3 schools are maintained by "our" shop at the Airpark, Aerotech. I know nowt much of the others except that you could et some good deals with Almat depending on when and often you fly.