Since the dropout is essentially cracked in half already, you need to have that fixed. I'm not sure I would feel comfortable just getting it welded again. I could replace the dropout, but the frame would have to be nearly free before I would be interested in buying it. For me, $20, for someone else, $50 max. And that's a maybe. In the U.S. that costs up to $200 to replace the dropout. Not sure about U.K. builders. You could get a local welder to weld it again from the other side for considerably less, but I think I would limit how far away from a train station that I rode it.