As a 31 year old Business undergrad (2nd year), I can tell you how I dealt/am dealing with things financially.
nb: I don't have any children, not married, and not in a position to live with parents (divorced and no space at subsequent homes).
Throughout my first year, I was already lucky enough to have a job (I worked at HMRC for 10 years, then went part time, reverse term). Entering my 2nd year and realising how intense the year would be, I resigned and left. It was a massive decision for me, but the main reasons why i left apart from the fact I wanted to commit full time to my studies, was that i was desperately unhappy in the job anyway, and I wanted to have flexibility in my life (during the summer periods) as to where I would like to work, or perhaps maybe travel/stay with relatives. I gave up a £500 per month job (HMRC), but knew i had financial support in the form of Maintenance grant, student loan and bursary which totalled £8000 per year.
I have had the odd part time job since I resigned from HMRC last summer, but I realised that uni was so work-intensive and every hour counted. So at the moment I don't have a job, but plan to as soon as exams are over in 10 days.
How do i live?
I live in a professional houseshare - and suggest you consider this option, and NOT student houseshares. I specifically wanted a professional houseshare because i wanted peace and quiet most of the time. If you receive full financial support, you will get the same as me (£8000 per year), which is about £3200 for maintenance grant, and £3200 for student loan, plus uni bursary (their own pot of funds specially for mature students with little or low income).
My rent is £250 per month plus gas and electricity, which equates to £50 per month. So £300 all in. So that's £3600 per year. The rest is obviously on food and socialising etc. It can be done without a job BUT you need to be amazing with money management. I always pay my landlord 3-4 months rent up front whenever i get my loans through.
I really do advise though to seriously consider not having a job in 2nd and 3rd year because there is an AWFUL amount of work to do, and you'll realize every hour in the day counts.