I've always gone to Pro Tyre down at the bottom of Lawrence Hill. Not sure how reputable the chain is but I've always had good service from them.
Obviously this won't be a "full geo", but do you really want your spring rates, rebound dampners, droop, etc etc played with, or are you just after a proper 4 wheel alignment (toe, camber, etc)?
If it's actually "full geo" you want, then no idea.
If you're after a proper track suspension/geometry setup I know a few round this way, but if you're just after basic alignment for a road car then I don't have a clue.
Which ones?
I'm getting coilovers fitted next week so once I've messed around with the ride height I'll need a good geo place. Was gonna go to Powerstation but if there's somewhere closer I'll maybe try them