Lancaster are quite generous about people missing their offers, especially in under-subscribed subjects, but my feeling is that you are probably asking a little bit too much.
Yes, they do accept Gen Studs, but as one of three A2 grades, not one of 4. You are offering BCC which is three grades below offer. I do know people who have got in with 3 dropped grades, and more, although not in Psychology. Don't give up hope yet.