Ian,
I think the thing with the schedule services (31k) is to make sure you know what you are getting - at the very least they need to do all the recommended service items and ideally change fluids + sparks (new Denso's presumably when they arrive) as well rather than simply inspecting them. Just on the major scheduled service, I think you will be looking at just over £1k +VAT + maybe factor in other bits and bobs / tyres etc.. which may need replacing.
I have heard good things about Autoshield and Marios seems to be very much in the know. I would have taken mine there, but the logistics of taking mine somewhere in Birmingham was a lot better as I work down there.