Hi, welcome, again. To answer your questions.. You need a provisional licence and to have completed the CBT to ride anything up to 125cc, this needs to be renewed every two years. You don't need to have a full driving licence. For a full bike licence you'll need to complete the CBT, pass a motorcycle theory test and mod 1+2 on any bike over 500cc. You can do the tests on a 125 but you'll be restricted for 2 years to 33bhp, currently you don't need to re-test after 2 years but there are new laws coming in next year. If you don't want to pay for a DAS course, you can always have lessons once/twice a month and spread the payments that way. It only took me 2-3 months, including doing CBT and theory tests. I think I paid a total of £600. There is nothing to stop you from doing the CBT, theory and mod1/2 without taking lessons but there is a good chance you'll fail without any kind of training or riding experience. More expense if you have to do more than one test, they are currently around £75..