VP8 - Sorry for the rather flippant last reply, bad attack of sour grapes.
To answer your question, the tests mentioned will be the usual raft of literacy and numeracy tests usual at interviews these days, plus you will be required to answer some simple problem solving type questions.
Nothing to panic about, if you have the organisational skills Jet2 are looking for and you can project a confident image plus a good knowledge of Ops, you should have no trouble.
These, plus a willingness to work in Leeds and you are onto a winner.
Best of luck
ILS