Hi T Father
There are some really honest (though might not be what your son wants to hear) good & fair advice given on the various replies given here.
I repeat go and get a Class 1 medical ASAP & keep the flying lessons going.
Up to 3 years ago I was a ground school instructor (TKI) at several of the big UK schools over the last 22 years. My last school did have some under 22s there even on the EasyJet MPL scheme (usually maths or science graduates) at the time but they are extremely difficult to get on & despite what they might tell you still offer no GUARANTEED job. I was instructing at Oxford when 9/11 happened and within 48 hours Aer Lingus had cancelled their fully sponsored course shortly followed by British Airways cancelling one of their fully sponsored courses leaving a lot of very unhappy students some of whom had given up existing safe careers, so much for a GUARANTEED flying job. These were probably the last fully sponsored airline courses, I believe all the others require you to put some of your own money in first to reduce the airlines risk exposure.
You will only hear positive spin from the sales people from the school but I have also heard of a few parents houses being repossessed & a handful of students being declared bankrupt after spending £100k+ but can't get a job to cover the debt.
Beware of the 'selection process' for these integrated courses, it's tame compared to the selection for flying in the UK armed services. Yes there are tests & interviews etc but probably the most important question at the end is "Can you write a cheque for £100,000"! Myself & other instructors were alarmed at some of the trainees who had been 'selected' who clearly from day one shouldn't have been there on ability (just there to boost the sales figures). These trainees often ended up being back-coursed or even eventually terminated, the services would have chopped them long ago, but we are in the murky world of commerce.
To end on a positive note most students will get through the training but it requires 110% COMMITMENT & FOCUS along with an almost non existent social life for several months.
All the best
Richard.