If you are doing the 2 days of training on the larger bike prior to the MOD 1 and MOD 2 tests then you should get enough experience to handle said bike for the tests. As above most people find the larger bikes are more stable and easier to ride. I have never ridden an automatic but I would think it should be pretty straight forward and you don't have a clutch or the possibility of it stalling to worry about. As the tests and training are all booked go for it and enjoy. You can always go back to do the tests later on manual bike if you ever desire, obviously at extra cost. The Honda bikes with DCT (automatic) are well spoken of so you should be able to get one that suits you.