I had no idea what I wanted to do when I was 18 so I went to university and came out with a ton of debt and no job and then I started from the bottom, it was 4 years of my life wasted. The current system doesn't work and it still won't work even if fees are free because the fact is the country does not need more people with university degrees.
Older people had free or cheaper university fees but that misses the point that is less older people went to university at all, many of them were working at 16. Somebody who started work at 16 will have 5+ years of experience and earnings in the bag versus a university leaver.
How many young people are in full time work today at 16? It's basically zero. Young people nowadays are only starting work in their early to mid-20's, is it any surprise that they can't afford houses? How can you save for a house when you are 21, getting pissed every night, lying in bed and attending a handful of lectures per week whilst you pay for it all with money you haven't got?
The university system is the greatest marketing scam of the last 50 years. It has made parents think that without a degree their kids can't be successful and a degree is critical to get the top jobs, it's not true. The biggest companies are begging for kids with experience, skills and a good attitude, they do not care about degrees because they'll pay for them to do degrees if it's really needed.
National service is perhaps a bad idea but only because of the military aspect. The idea of getting kids out there to gain experience, skills and do something fulfilling is an extremely good idea.