If I was to be unlucky and fail the Class 1, would I automatically get a Class 2 ?
That would depend ENTIRELY on the reason for failing.
In some areas class 1 standards are simply a bit stricter than class 2, so, for example, if the class 1 vision standards were just missed, the class 2 ones might be met.
If you were found to have unsafe CVD, you could still be offered a class 2 with the "
daylight flights only" limitation.
There are, however, other reasons for failing a class 1 where a class 2 would also be totally out of the question. For example, any kind of epilepsy, many cardiac conditions, or insulin-dependent diabetes.
It's a good idea to go for it now, and find out. Only that way can you plan your whole future career better.
Good luck with it !