Thanks for the heads-up on the Forestry Commission site, I hadn't checked on that this year.
I may give Velvia 100 a try, although whether I'll do it in 120 is another matter. I tried Velvia 50 through the C330S last year and the palette of the slides looked very different to the one I get when I use my F80, and not in a good way... <shrug> Hey ho. I might try a roll of chrome through the Rollei 35!
Lab-wise, I've always had extremely good results for E6 from -
Metro Colour Labs
Unit 2, Summer Hill Industrial Estate
0121 212 3334
Turnaround was always quick, prices were always competitive and they'll do you prints too. Given the current economic climate though, I'd give them a ring before sending your stuff off just to make sure they're still there...!