Estonian Air - Gatwick
easyJet - Stansted, or from other airports via Berlin
KLM - local airports, via Amsterdam
WhichBudget - to check out all the options
There's a bus service from the airport into the city, which is about 4 km away. The stop is outside the departure area of the passenger terminal. It's the number 2 and it runs every 20-30 minutes. You get a ticket (15 EEK) from the driver.
Guides & info
Tallinn tourism site (good site)
Rough Guides (select Tallinn from Featured Cities pull-down menu)
LateRooms.com (Kalev Spa looks really good!)
Club and ground
FC Levadia are currently the strongest team in Tallinn. They play at Kodustaadion, which has a capacity of 4,700. However, they tend to play European games at Le the national stadium Coq Arenal, which holds a few more. The ground is a mile and a bit south of the station and old town.
FC Levadia official site (in Estonian I'm afraid!)