If you passed your car test post January 1997 you will not have the category B+E on your driving licence.
To tow certain trailers you will need to take an additional driving test:
A full car licence (category B) already lets you tow trailers weighing no more than 750kg. You can also tow heavier trailers with a car as long as the total weight of vehicle and trailer isn’t more than 3,500kg.
If the trailer or combination is heavier than that you will need to take the B+E driving test.