Willow Fabrics https://www.willowfabrics.com/ sell embroidery goodies. Quite a bit dearer than Lakeside where the Mill Hill beads are concerned, though they do sell, when they are in stock, a wider variety of them.
The Viking Loom in York https://www.vikingloom.co.uk/acatalog/index.html sell needlework items. Since they moved from the centre of York I haven't been to the shop as it is way out of the city, need a car to get there.
Wye Needlecrafts used to be good, the best place to buy speciality threads from in fact. They seem to have very little in stock these days. https://tandemcottageneedlework.com/ are another online shop, they don't seem to have a great deal either, though at least their DMC threads are reasonable. DMC sell their own kits and threads. Then of course there is Jane Greenoff at The Cross Stitch Guild. The Nutmeg Company, perforated paper kits, plus perforated paper packs.
Nearly forgot Fun2Do in Carlisle. They say they specialise in mail order, but I didn't think much to their website to be honest. The shop doesn't stock much that I want either, neither does The Silver Beaded Needle in Cockermouth. Didn't bother going to Cockermouth last time we were in Carlisle.
Well it is a start! ;)