I've flown out of both Leicester and DonAir at East Midlands, and they're both great places that I'm happy to recommend. The main differences relate to the club aspect - Leicester has a really strong and friendly club atmosphere while DonAir is friendly with good people but isn't really a club.
The other big difference is the operating environment - big controlled airport or basic uncontrolled airfield. The former develops confidence from the start in dealing with controllers and big traffic, but can also mess up lessons with delays and long taxi times, plus you're spoilt with a huge runway. The latter is much more dependent on you making your own decisions, circuits can be nice and tight if necessary and you'll be much more confident going into smaller strips, however you might be less confident with dealing with controlled airspace. None of these issues are insurmountable...
I don't really know Nottingham that well, it always seemed pretty quiet when I've been in there. It's probably worth a look to get a feel for yourself. There is also Tatenhill to consider, again not flown there but I have flown with the guys from Central Flight Training and they seem to be very professional in their approach to aviation.
I'm biased, since Leicester is home turf to me. But I've tried to be as fair as possible. Bear in mind your commuting distances too.
Welcome back to flying...