Gissa
It's not impossible, but...
The nature of the Jet2.com operation means that you would need a minimum of 40 sectors to get through line training. That is a lot of flying during the off season... This will be a BIG barrier to you. They may take it is an "advanced JOC" (my definition) and so put you on the B737 if you pay for the TR - they work much harder and much more frequently during the winter so the 40 sectors isn't so much of a problem.
Don't give up though, there are all sorts of weird and wonderful contracts out there, and luck seems to play a large part in it.