I went to an open day at a big integrated school and had a conversation with a parent on the 'university or not' debate. I get involved in recruiting from time to time in my job for new police officers/PCSOs and civilian staff.
My view is don't go to university for the sake of simply having a degree. If your son is bright and can get in to a 'good' university (one that big employers will take notice of, i.e. Oxbridge/red brick) then by all means go. But bear in mind at the end of the 3 years there will be a debt here as well - average is approaching £20K now.
I have no wish to offend anyone in terms of the choice of uni. I am simply saying that for a wannabe pilot with good A-levels, a degree in some lightweight subject from a uni (ex-poly) and £20K of debt to go with it is probably not a good investment. Personally, I would be more impressed to see a lad of 21/22 with 3 years of work experience where they can demonstrate their development and evidence their workplace skills rather than someone the same age who has spent 3 years getting a degree that really doesn't mark them out as anything special. This is part of the issue with Nu Labour - far more people go to uni, so a degree in itself is not the big thing it once may have been.
And BTW - on the subject of groundschool - he could of course do it full time in about 6 months if he didn't want to go to uni. Depends how disciplined he is likely to be doing it distance learning? Cost would be a bit more maybe £4K inc the exams, plus accomodation if req.
Good choice for his PPL - I did mine there!