First of all, welcome to UKY! I'm sure you'll find all sorts of great info here. You should pop by the Welcome Wagon and say hello so people can get to know you.
I'm afraid you won't be able to work here just as a visitor. You'd have to have some sort of work permit (which is hard to get unless your company is transferring you) or a settlement visa (which is for marriage, etc.)
But once you get one of those, you definitely don't need a college degree to work here....especially in entry level positions, and definitely not if you're planning to continue as a temp. Here in London, temp work is easy to come by...degree or no!
How long are you planning on staying in London?
Hope that helps your stress level a bit anyway!