First, congratulations on pursuing your interests for a career, a lot of people never take that plunge!
Is the loan through Student Finance England (or similar government body)? I always say that people should never think of those loans as being "proper" loans, because the repayment is so dependent on your earnings, and its not like the debt collectors will ever come round and start taking collateral. The repayments are pretty negligible too, definitely just like a small tax added on to your pay slip, so really nothing to worry about. If you can comfortably take the financial hit of self-funding then I guess that just removes the ongoing cost of repayment, but frankly I think the loan is the better option.
Anyway I'm not a mature student but I've done a BA and MA, and there have always been mature students on those courses. In my experience they integrate really well and can offer tremendous insight during discussions etc. My recommendation would be to take the initiative and strike up conversation first - I think younger students might be a bit intimidated by your age and wouldn't know how to approach you (more out of anxiety than rudeness), but if you just start talking, asking questions etc, all of that inhibition will drop.
On my BA there was a lawyer, somewhere between 40 and 50, who had been forced into law by his parents but had always wanted to study history, and had finally just decided to go for it. He kept on the sidelines for a bit, not quite sure whether anyone would want to talk to him, but pretty soon he was coming out for coffee with the rest of us, and eventually you stop noticing age differences altogether.