I have the forms as well and am in the process of completing them, just waiting for my official confirmation of a place on the course. I don't know which will process the application quicker, but I was going to go with Barclays as I went for a little meeting there recently and they have a good graduate account, not too sure about the Co-op.
However after looking at the form in more detail I'm not too convinced that they will pay out for a MSc course, they seem to be more geared towards vocational courses like plumbing or whatever - am I right? My course doesn't even have a reference number and its purely academic so I don't think I have a chance, I think I'll just go for it anyway though, its worth a try. How can you find out whether your course is eligible?