My local Jessops was recently listing a Tokina 19-35 used for the same
as other retailers are new.

My local LCE has gone downhill a bit last few years unfortunately, not a
lot for the SLR person in new or used.

I second the other posters AJ Purdy recommendation, I've bought very
happily in the past from them, and everyone else I've spoken to hold
them in high regard, even if they aren't quite the cheapest by a few
quid [1] I'd still go with them for the quality of customer service.

[1] Although on the items I've bought they've been pretty much on the
nose price wise.