I didn't even know Surrey did ChemE. I did know Leeds had it, with several options of specialisation (including I believe nuclear, which is pretty uncommon in undergrad), which might be telling...although I did know Surrey has some nuclear options in it's Physics programme.
However I'd probably be inclined to suggest Leeds, although this is pretty much just based on the fact I've heard more of it wrt Engineering, whereas Surrey I only occasionally hear about, at all...and get the impression it's sort of "fading" bit :x
Regardless, Leeds isn't a bad university by any metric, or for ChemE in particular, so if you're otherwise happy with the course and location, I see little reason to change now.