Florence is the nearest airport (40 Kms) but Pisa is also close and convenient in particular for budget flights such as Ryanair/Easyjet.

Nearest airports: Florence - 35km, Pisa - 127km (main*) or Bologna - 141km.
Nearest trains: Figline - 8km (mainline trains from Milan/Rome)

Airlines and airport guide:
EasyJet and BA fly Gatwick to Pisa;
Ryanair from Stansted, Liverpool or Glasgow to Pisa;
Easyjet fly Bristol to Pisa;
ThomsonFly.com and Jet2.com fly to Pisa from various UK airports;
Merdiana flies Gatwick to Florence.

* There is a very good train service from Pisa to Florence, from where you can then rent a car if you wish.