Do whatever you can - if you must go sick for another interview - then do it - there are many airlines in London ( and all over the UK) ...... forget about Ryanair - they seem to be a very difficult airline to work for - from what I have heard - crew are worked too hard and very little pay. YOU control your life - NOT Ryanair - just go sick if you have to - if you can do an interview on one of your days off - all the better - but go sick if you have to. It seems the only way. Your future depends on it. Good luck.