I've now switched to Sky - the confusion lies due to the fact that they can't put me on the SVBN network, so I've been connected to the old Easynet kit at the exchange and even though my line is with Sky, it's actually BT who are provisioning it for the time being.
Apparently I'll be migrated over to SVBN eventually.
Still frustrating about the fibre though as I know of at least one person in Leamington who has Sky Fibre, but he was a triallist so they probably just don't have enough kit in the exchange.
Pleased with the speeds btw - my 10-day DLM finished today and the downstream noise margin was stuck on 13.5db, resulting in a rubbish 12Mbps. I gave them a call and they promptly gave it a kick so I'm on a very low 3db but this gives me 18.8Mbps so much better than I was getting with O2 (or Bulldog/C&W before that). Just hoping it's stable as 3db is a tad low but it's been up all day so far.