Okay, then I guess I just need to make sure I have a large enough loan. Are there any websites I can use to calculate what immigration will expect me to have?
If you check out the International Students pages on the websites of the universities you're interested in, they will probably have sample budgets and estimates of living expenses - looking at the international handbook for Exeter Uni (my undergrad uni), they estimate that a single person in Exeter needs about £650/month (£7,800 per full year) to live on, whereas Birmingham university estimates £7,800-£10,800 for one person. If you're in London, these estimates will be higher as living costs are generally higher there.
Basically, you have to show immigration that you have enough money to cover the tuition costs plus rent/food etc for the duration of the course (so if tuition is £10,000 and living costs estimate at around £8,000 - you will need to show you have access to at least £18,000 without needing to work in the UK). Bear in mind though, that even if you apply for as large a loan as possible, there's no guarantee that you will definitely get this amount - you may do, but nothing's definite until it's approved.