Don't forget you've got 2 types of test for your big bike licence, direct access and restricted.
It sounds a lot more complicated than it used to be. Direct Access. :-/ What's that supposed to mean? Who thinks up these stupid names?
http://www.elitemotorcycletraining.com/licence_options.htm
From that site it said
To be eligible to start training, you must have a full UK car licence, a provisional UK car licence with valid provisional motorcycle entitlement, or an EU licence with valid UK counterpart (D58/2) showing provisional motorcycle entitlement.
Do you need to pass a driving test before going for the bike test?
All seems to confusing

When you apply for a provisional license, it is for car and bike. If you pass your bike test, you get a full bike license that is provisional for a car. If you pass your car test first, your full car license is also a provisional bike license. Also get provisionals for, road rollers, some HGV's, caterpillars and a few other non-normal vehicle types ...............confusing isn't it

Matt