Have you thought of applying for Virgin and commuting? A lot of people do it,so its not impossible. Im sure there are plenty of other carriers "dahn sarf" where it would be feasible to commute - Silverjet,maxjet,Virgin, BA if they start recruiting again for Long Haul, Air New Zealand, Qantas, Zoom...you get the idea.There is plenty of choice. Given that youre in glasgow, edinburgh isnt THAT far, why not see who is recruiting there?Theres always BA Cityflyer from Edinburgh or Flybe are most likely to be recruiting.
At the end of the day, youre only 20. If you have to wait a bit longer until maybe next summer, then do that.Its not like you would be too old to fly!!!!Once you are 21,it will open up more doors for you.
If youre not happy,do yourself a favour.
Good luck.