I was in a similar position to yourself 3 years ago.
I wanted to take it at my own pace, but also wanted to get the license sooner rather than later. I did my CBT, went out and bought a bike, and then did my test when I felt ready. CBT I passed August, Test October.
I wanted a 125 on that basis, and ended up picking a Honda Varadero, which doesn't look anything like a 125, but is really easy to ride. I kept for 3 years as it did everything I wanted, only selling it because I want a car. If you do things at your own pace you'll become a far more skilled, confident rider, than simply picking the biggest bike you can afford/insure, and then taking it into the nearest ditch.
Hope this helps a bit