You need to do a CBT to ride any motorbike, it costs around 100 quid. A CBT lets you use a 125cc bike with L plates, and no passenger a CBT and a full car license gives you the power to ride a 50cc with no L's - The test, (the full license one, i mean) it costs a fair bit, rather like the car test. You'd not do badly to do a crash course, the reason being that i think in october the test changes to be harder, and for you to have to visit training centres that will be few and far between. I think a 125 can go on the motorway, they can nearly hit 100, or just over, so they'll go on one. Insurance will be way cheaper than a car's, the tax is cheaper and bikes are more efficient so the petrol will cost less, unless you buy a 2-stroke, lol.