Gaz
Listen to the advice above; it's good. I'd like to add a little bit more about the military route.....
Do not approach the RAF, Army or Royal Navy with the intent of trying to use them as a short cut to the airlines. It won't wash. The Services require 110% commitment and loyalty right from the word go, and will see through anyone who applies with the intention of leaving early to join the airlines. Also, it is not within your power to choose which kind of aircraft you fly; that choice is dictated by the Service you work for.
Having said that, if you decided that you would like to do a 12 or 16 year commission flying within the Services, at the end of that time you would be well placed, and welcome, to join the airlines.