In terms of entry criteria and what you might be expected to have, here is what the last group on the Thomsonfly course at Jerez I think have roughly:
1 Potential RAF Fastjet who failed final Medical, Degree - 100 Military Hours
1 Military ATC, flying UAS, Degree - 80 Military Hours
1 Civilian ATC, flying UAS, PPL, Degree - 100+ Hours
1 PPL, flying UAS, Degree - 75+ Hours
1 TFly Cabin Crew, Degree - 30 Hours
1 Ground Handler Servicair, No Degree, - 40 Hours + 70 Glider
1 Aeronautical Degree from a Top Uni - 0 Hours
1 Engineering Degree from a Top Uni - 0 Hours
So what can you assume based on that, well that you don't need a degree but in that case some strong evidence of a committment to flying. If you have no flying experience then a strong academic pedigree preferably in aviation. The preferred I think is some flying experience and a degree, as you would probably expect so the airline can minimise risk.
Hope that is of use. It's not to put people off but more as an idea of what a recent course standards were.