Student Finance works the same way for mature students as for school leavers. As you are under 25, your parents' income will be taken into account, unless you can demonstrate that you have worked for 3+ years. If you do Access starting in 2015, you will qualify for the 24+ Loan, as you are 23 now.
As Conzy210 says, top unis don't give offers based on UCAS points, but will ask for specific grades in whatever course(s) you are doing. Also, their requirements may be different for mature students, as they consider them on a case-by-case basis, so UCAS points aren't really that relevant.
There are plenty of good universities that aren't Russell Group: RG is just an organisation of research universities that banded together to protect their interests. It is not necessarily an indication of quality, so it's worth looking at other unis too. I think you should pick out a few that you are interested in, and then email the relevant admissions tutor, explaining your circumstances and asking their advice on how you should proceed.