Telecomms is my day job, and I'm regularly involved with situations like this. At the risk of stating the obvious, have you considered running an external-grade cable from the master socket to the new location?
I've blogged on this. Search "how to move your master socket without actually moving it", and you should find it. If I still lived in Sawley, I could come and do the work!
You should not lose much speed down a decent-spec cable. Plus,if it's coming off a fibre cabinet not too far away, you'll will be starting off with a decent speed anyway.