As long as you turn up you will pass.
…and you aren't a numpty! There was someone who failed on my course. She was so bad that, in my view, she should never be allowed on two wheels for her own safety.
i have riden a moped around my house
Wow! Big house!
CBT is simple and fun. Almost all pass it. You must listen and not assume anything.
After this, when you have your bike legally on the road, be VERY mindful of the potential dangers of using a public highway in your early years of motoring. Feeling invisible is probably the biggest risk for a rider of your age. I apologise if i am being presumptuous, i don't know you or your temperament, but I from my opinion from statistics and personal experience. There is much to learn, even for older experienced road users. Bear this in mind, always!
The risk for two wheeled vehicles is vastly higher than for those with four wheels. Making mistakes and having an accident on a bike always ends in at least a minor injury if you haven't got a full set of bike clothes – get decent gear!
Some people I knew didn't get a second chance! So my advice is be afraid of what might happen, very afraid! That will give you the best chance of becoming a good rider by gaining the experience you can only get by being out there. (I don't mean scared and hesitant, these people are at increased risk too. You will learn about this on your course).
Get some books on biking. Your instructor will recommend some. In my early years, this reference saved me from a few nasty accidents.
Consider doing a DAS course as soon as you become elligible. YOur instructor will advise you on what age you need to be and what level you can go to.
Good luck and most of all BE SAFE!