Wow, all week and a Saturday???! I was told it was just Fridays. That's good if it's all week -
I know you've just said Saturdays is from Newquay.
If that's all week (including next year) - I may have to go on a Monday, Tuesday or Wednesday to Edinburgh
! I'm going for 5 nights but on a day where I can catch either an HST or double Voyager back to Oxford any South West-bound train from Edinburgh via Birmingham New Street where the 65-70 minute trip is on a 4 or 5-car Voyager rather than the 5-hour stretch which I'm aware could be a single Voyager substituting for a longer train.
I'd catch an LNER to Newcastle, Darlington or York. Problem is, if my seat is backwards to Birmingham New Street there may not be many good alternatives - whether as if I change at New Street, then I'll stick with my seat reservation.
Backwards trips on Voyagers isn't bad but more preferable on a more spacious train or for up to say 60-70 minutes / not too long on a Voyager.