It does depend somewhat on the course.
I've just had a look, if I'm not wrong SD's household income is a little less than ours, at £45kish, and the calculator tells me that would be £7500 a year in maintenance loans. I looked up Liverpool Uni halls and they start at £6,756 a year (£173 a week for term time only).
That leaves £744 which is obviously nothing like enough to live off. However, even if you have a very intense course, you can work over the summer. Even 4 weeks of full time work at NMW could save £2k, and students usually get around 12 weeks off so I don't think 4 is crazy, even if it takes them a while to find work. So that's £50 a week for every week of term.
If you can work even 4 hours a week PT, that's another £50, and I think £100pw should be enough to live off shouldn't it?
If parents can chuck in some money for a big supermarket shop a few times a year and cover train fares, I think that wouldn't be an uncomfortable life.
We will be giving SD monthly money when she goes to Uni but it won't be anything like the figures floated on here of £500+, we just don't have it.
Re dentistry and medicine, you do get a bursary for those.