Hi Tim,
Just quickly, my responses to a few of your questions. I trained for my ATPL(A) in 1998, so I might be a little out of date. I don't mean to sound callous or cynical but I will be brief.
There is no free ATPL training to my knowledge.
£70,000 for an ATPL seems optimistic. Type rating will cost up to £30,000 on top. I have heard of £125,000 in total.
Wannabe pilots basically have to decide between paying for their flying training or getting on the housing ladder. It is taking a big risk to assume that all will be successful and pilot salary will repay all debts.
Won't walk into a job, (no experience).
Probably will have to pay to be offered a job. I have 22 years experience and am Airbus type rated, but just two years ago, a certain low cost airline said I would have to pay them £8,000 for a job at a foreign base.
Salary expectations seem over-optimistic. About half that would be more realistic for the first few years.
Lots of hurdles and hoops to jump through - even if you have an ATPL and a type rating. Even if you have many years' experience.
Piloting is not as much fun as it was. Fatigue, difficult schedules, getting up at 0300 five days in a row, or not getting into bed until 0300 five days in a row.
Becoming a pilot needs four things:
Class 1 medical.
The money for your training.
The ability to fly, and to learn and pass all the exams - written and practical.
Luck - by which I mean being in the right place at the right time with the right airline (for you).
Get the Class 1 medical as soon as you can, before you start anything. No medical, no job, so you need to know if there are any underlying health issues before starting.
Again, I apologise for not presenting my answers very gently, but I wish your son well, I honestly do. It will be an enormous outlay though.
Good luck.