A few years ago, virtually all airlines would help out with expenses, even give you tickets on their own airlines or one of their code share partners etc. accom was usually up to you though depending on how far you had to travel I suppose.
I interviewed with Atlas Jet early on this year and I had to fork out for my own hotel/ flights to from Istanbul etc. The Sim was paid for by them but nothing too tricky if you had done your home work.
As an earlier poster has mentioned already, you have already been "Interviewed" by them, obviously without you realising it. These sort of interviews are unusual in UK ( but do happen) normally over the phone but these days also over the Internet too!
It depends who you are considering going to work for and the distance involved really. Sounds like providing you don't "Disgrace" yourself, you should be OK. I nearly went to Atlas Jet but had a better offer a few months later whilst I was awaiting Work permits/Visa and things.
Had I not had the other offer I would have certainly gone to JED with Atlas. A friend of mine decided to go with his family and he is really enjoying a different way of life for a couple of years.
This Life /Career is what you make of it or not, as the case may be. Sometimes sacrifices have to be made in the short term for a longer end game.
Good luck on what ever you decide to do.
BR.