Tanks-A-Lot
The guys at Tank-A-Lot are probably the leading Tank Driving guys in the UK.
They have 95 tanks that can be taken on their off road tank driving course. They specialise in tank driving, corporate tank driving (not over your boss, although if you bung them a tenner they may let you drive a tank over his car) 
Other than the tank driving experiences that are on offer from Tanks-A-Lot they can also arrange the use of a Tank for other activities you may require, how about a Tank Limo, or you may need a tank for a publicity event.
Tanks-A-Lot is in Helmdon, Northants, not too far away from Silverstone.
Tanks-A-Lot
Spring Farm
Helmdon
Near Brackley
Northamptonshire
NN13 5QD