I also wish i'd taken my test @ 17 when all you had to do was get on the thing & not fall off but after my Fizzie the new KH250 felt & sounded like it was going into orbit....once the centre pot cut in!!!
I went from a Fizzy to an S1, and as you say, what an animal once that centre pot caught up

I can't be arsed to go through all the theory/haz aware B/S & the hundreds of pounds it costs to be patronized/passed/failed by someone who was'nt even born when i was riding,i just can't handle it & don't want a screaming fast bike.
I was one of the last to take the original "ride around the block for 20 mins" tests before all that circus performing seal rubbish was introduced, cost me £12 IIRC.
So it's a 125 & renew my CBT or take the test, no other way round it? 
Fraid so, but you'll be restricted to 125cc if you don't take (and pass) the test.
If you are 21 or over and choose to take the "Direct Access" test and pass, you can ride whatever you like.
If you are under 21 and take (pass) the Direct Access test, you will have to wait until you are 21 (or 2 years has elapsed) before you can ride full power.
Note that the 33BHP restriction is nothing more than a bit of paper from a motorcycle shop that says a restrictor kit has been fitted to your Hayabusa Turbo, nobody actually checks how many horses you are laying down