I think it sounds like a recipe for disaster.
You will save money but at what cost? It only takes one of your flatmates to come home early and you could be out on your ear.
I can't advise on the relationship side of things.
Obviously, I don't know your situation and apart from saving money you might have other reasons for wanting to move. On a positive note, if you are willing to take a chance and save up for a work flat then the benefits might outweigh the risks.