CBT = 'Course' rather than test, once you pass you get learner license = 125cc
or less, less
or equal to 14.6bhp.
Yup 
A
(restricted) test = Any bike ( at 33bhp
or less )
then I can either wait 2 years and I can ride anything OR take the DA test ( which I cant because you have to be >21 ).
Yup
Ok then, another barrage of questions for your infinate wisdom!
If I were to do my CBT, then my A course ( without buying a bike ) I can buy anything, but obviously little point in buying a very powerful bike, as you said I'll be bored with it in 2 years anyway. So what bike would be a reasonable ( eg as near to 33bhp as possible and decent! - I like the 'sports' bike look )
Thats a big question in its own right, and im not really a 125cc guy , ill ask about though.
A Test, can I use their bikes again? What does this entail over the CBT?
Its usualy a course thats a few days long. Length of said course depends on how many hours you do a day. You can usualy always use their bikes, although a hire fee is common for most things above a CBT. A riding school that doesnt offer bike use is a bad school.
Also, having looked on autotrader for the bike Michael has, it appears ones with as few as 10k miles have had the engine rebuild already?? Is this normal for bikes, or this class or bike? if so does that not hugly ramp up the cost of them?
Depends on the bike / engine. Check wikipedia and read up between 2-stroke vs 4 stroke engines - they can differ a lot in regards to rebuilds. Somthing like my ER-5 wont see a rebuild for a long time, a motorcross one used in races can have a rebuild after every race.
Thanks for everyones replies, I really appricate all the help I've gotten here so quickly!