The above poster is probably correct. If you have and are willing to part with a fortune, you should be okay with the interview.
As for potential resources: Compile a list of your target airlines (Ry, Ez, Flybe, Jet2, etc - Oh, and BA and the like) and have a look at their official estimated annual growth figures and fleet expansion plans. Easy, for example, are predicting a 3-5% annual growth with 135 (?) new A320's on order (They have some power point presentation on the internet for shareholders and the like).
This should be used as research in to your future job prospects (or lack of) too. For example, digging deeper in to the above figures shows that a decent proportion of the shiny new A320's Easy will get in the coming years are replacing retiring aircraft and thus, no extra jobs will required for these aircraft.
Goes without saying I hope, but ensure you critically analyse the sources you find. For example, anything that the FTO's tell you about "Pilot Shortage" should be considered nothing more than marketing spew (They are a hugely biased source. I bet you didn't buy anything that the Russian state funded news agency had to say about Ukraine!)
Also take a look at the "Pilot Shortage" issues in China and the like - how does this affect you? How does the (somewhat) recent upping of the retirement age from 60 to 65 affect you and your prospects? Pay To Fly (not advocating)?
No one is going to give you the golden nugget - you must be prepared to spend an awful lot of time researching this industry and you have to come up with your own reasoned and objective answers.
This assumes you actually care about the state of the industry of course. You won't (although, I don't speak from experience) need this level of depth (you could probably get away with saying "low cost airlines are winning, legacy struggling") since OAA, by rejecting your application, are loosing out on a £90-120k payday. But it is interesting reading nonetheless.