It depends so much on the individual. I went away to university at 16 and was fine. It helped that the institution had a tradition of accepting young students and there were a handful of others around. There was the expectation that we would cope but might need a bit of extra hand-holding. Some did struggle.
I may have found it relatively easy because I was used to doing housework and helping my parents with their finances: they'd done my sister and me a great favour in our early teens by having us help balance the chequebook and pay the bills every month. The main challenges from which some of my classmates suffered were staying on top of their laundry, shopping, cooking and cleaning as well as managing their money.
Socially, we were not at all sidelined. Those of us who showed maturity were treated accordingly, while those who didn't were taken under the wing of some of the older students and looked after like younger sisters and brothers - bossed around a bit, teased occasionally, overprotected at times but still included.
For us, drinking wasn't the issue which some parents seem to fear. Those who wanted to drink did so illegally, just as they had already done at school. Those who didn't want to drink said no thanks, and probably came under less pressure to conform than they had at school. For me, university was a relief from the intense same-age social jockeying and exclusion which can happen within a fixed peer group such as school.
Living in university accommodation helped enormously. Like many young people, in later years I had my share of troubles with private landlords who took advantage and flatmates who ran off leaving me to pay the rent or other bills. With hindsight it was great to have been spared that for my first few years.
Hope your dd lands on her feet, KatyMac!