I'll contribute what I can to answer your quesion. However, my situation is quite unusual, so don't plan on using it as a model.
I'm a postgrad and I'm paying home fees. My wife is faculty at the uni, and part of her contract is that I get home fees, because that was a big issue for us deciding to move here. As I understand it, this is very rare. Apparently, the university here balances its budget on foreign students, since the home fees of a British student do not cover the cost to the university of one student. Every time I register the paperwork on my fees is wrong and I have to go fight with the office to get it changed.
Most normal awards are limited to UK or EU citizens, which cuts us out. At my uni there are some departmental awards which are open to all. They realize that foreign students are left out of many funding options so they try to direct British students to other sources and then give departmental awards to people who don't have anything else. Check with the departments where you are interested and see is they have anything.
I second the idea to contact faculty members and see if they can apply for funding. In the sciences, where my wife is, it appears the standard funding method is for the faculty member to get funding to support a student on their research grant. My wife has a (undergraduate) student interested in working with her this summer and they just finished sending out a bunch of grants for funding. Scale that process up for Postgrad work. Not all faculty will put in that much effort, but if you have one who matches your interests and they want you as their student, they will find ways to help you enroll.
I'm afraid I don't know anything about Open University other than their TV shows
Good Luck
David