Thanks so much for the useful tips, every body - very much appreciated, and reassuring. I went to test drive it today with a friend who has a lot of experience driving different company cars.
I bought it!
It drives incredibly smooth, and is a bit of a spaceship compared to my old car.
Everything seems high quality, and everything I could test work fine. All four tyres look pretty new.
I questioned the cambelt and they gave me money off to have it changed at my local garage (£350, which might be less than my garage will charge, but unfortunately they wouldnt budge; if it came to any more, they said I'd be welcome to return to them and have it done there. As it would entail another 4 hour round trip though, I don't think I'll bother!) They are also shipping a replacement key hole cover to me from the driver's door handle, as it was missing.
For those thinking that I've jumped in, I've actually been looking for a replacement car for months now, but nothing was showing up in my budget and vicinity, which matched the models in my list (based on boot size, leg room, euro ncap safety rating, service history, mileage.)
In truth I -was- getting a bit desperate, as the air con in my old car had completely broken and required a new motor box, which wouldn't have been economical to replace at a quoted £1000. And I didn't want to risk long drives to visit family in the old car, as I didn't trust it would get us there!
But yes, luckily the new Skoda has ticked all the boxes, and the 2 hour drive back in it cemented how nice it is to drive.
Fingers crossed for some good years of motoring ahead in it.