Any question answered...

Definitely seems worth mending.

I mean using a quick google-fu I can get the seat clamp and re-track done for 100 at Mercian.

I don't really want to pay courier so something within reasonable driving distance would be cost effective also.

Check the usual frame builders in London. Depending on their work load they might be more convenient (presuming you're in London). Ryan @ Oak straightened my Bob Jackson forks for a reasonable fee.