The good news is it's definitely not all over for you! Plenty of mature students, ranging from your age group to a lot older, have changed direction in life by going back into education.
First key area to investigate is what you want to study. Think about what you'd find interesting enough to study for 3-4 years at university (assuming that's the direction you want to head towards).
Second key area to investigate is how you can fund your studies. As a first-time HE student, you should qualify for SFE support for your degree (i.e. loan for tuition fee costs and loan for living expenses). You may find it a little more tricky if you do need to do an Access course to get into uni. Assuming you enrolled on an Access course starting Sep 16 or later, you'd be at least 24, so you'd qualify for the Advanced 24+ Learning Loan, which would cover your course fees. However, it's unlikely you'd get any support for your living expenses, so you'd need to think about how you would support yourself during that time (Access is usually 1yr f/t, although I believe some colleges offer Access p/t over 2 years).
Third key area to investigate is an extension of the second one: will you need to sell your flat? I suppose that really depends on whether you really want to keep it or if you'd be happier having a fuller student experience that would be much more feasible without the burden of having to pay a mortgage off.