Having just been through the interview you can have my two-penneth. I just really don't see how paying for an individual's help can be worth it. I mean - the replies to my questions and general help and info offered on this site (freely) was really fantastic and I've been at pains to thank everyone responsible (I made it through). But no one piece of advice or example questions came up. To be honest I was amazed at my technical interview - it just flew by and covered only a little of what I'd worried about learning. But I guess the point is that I had tried and learnt the things that another interviewer may have brought up.
As regards the personality stuff I suppose you could be given some stock answers but to be honest that's going to be seen through fairly quickly isn't it? I mean they aren't expecting automatons just some decent explanations and a bit of confidence getting them across. The computer tests you'd have to just practise and practise and I suppose you might improve but they're surely set up to test your adaptability at getting and applying information quickly. The main thing here is the breadth of experience that multiple input offers and the general community spirit here at PPRuNe is the real help (and those contact details for visits because NATS aren't helping there).
The idea of paying an individual for the service just seems pointless and a little arrogant of those concerned - to think that they have the magic responses for all applicants is a bit off and to be honest it would be a shame if people who want the opportunity as much as us hopefuls do were to pay for something that is far surpassed herein for nowt.
......
and relax.
