I did my test before all these changes, but what I did was cbt, bought a cheap yamaha sr125, poodled round on that every day getting some confidence, took my standard test then carried on with the 125 till the two years were up then climbed slowly from then. 250, 500, 750 then 900s (which I'm happy to stick at). You come across as very sensible and your plan sounds good. Get a 125 that you'll be happy to ride for a while rather than just trying to get the biggest, fastest bike you can as soon as possible. It's much better to make all of your early on mistakes on a cheaper low powered bije, and your riding skills will only improve.