As Aliturnbull said a lot of the airlines discriminate on the age factor. You will not find it anywhere in the black and white, but that is reality. Your age must be equivalent to your experience.
So if you are 40 when you come knockng on the door they expect a lot of experience if you wanna get on board.Keep in mind that there is an age limit in effect (in the US anyway-dont now UK) for flying for the airline.Tha fact is that most of world airlines hire people in their mid-late 20s or early 30s.But there are exceptions.
But who said that you have to work for an airline. There are other flying jobs out there. Well not right now, but in 2 years who knows.And you can propably make captain by 45 with some other flying companys like charter fractionals or maybe make a career out of flight instructing and become a pilot examiner.Etc.
good luck!
LC