If you've had a continuous licence since before 19/01/2013 you can drive vehicle up to 3.5t and trailer up to towing limit of vehicle; (DVLA quote)
"Vehicles up to 3,500 kg Maximum Authorised Mass (MAM). You can drive a vehicle with a MAM of 3,500 kg with a trailer. The size of the trailer depends on the BE 'valid from' date shown on the licence. If the date is before 19 January 2013 can tow any size trailer within the towing limits of the vehicle. If on or after 19 January 2013 can tow a trailer with a MAM of up to 3,500 kg within the towing limits of the vehicle"
You can check your licence online and the tabs will tell you what you can drive. You need your licence number and NatIns number:
Licence Check