I loved my uni days. I found the difference between GCSE and A level to be greater than the difference between A level and degree.
As for enjoying uni I think it depends on your personality and where you choose to study. My uni was a 17th century mansion set in several hundred acres of country park, with 2 lakes and our own nature reserve. I loved it as it was so me, I would have hated going to uni in a big city (wierd as I grew up in Leeds!)
As for the self study regeme, my 1st and 2nd year we had lots of lectures so I was in Mon - Fri 9am - 5pm doing lectures. My final year I had 2 hours lectures a week, but so much stuff to do on campus and writing dissertations that I put the same hours in anyway. As I did a music degree I still had to do 6 hours a day instrumental practice anyway so I spent a lot of time at uni. Some of my friends did not do this (too much night life and getting up late) but they paid the price in the end.
Oh and as for making friends, I met my DH in my 1st week at uni, started dating him 2 weeks later, we have been married 9 years this year (we married after I finished my post grad course.)
My advice would be to look around lots of unis to see which you like. As for the study regeme, that will sort itself out once you are there.