Tony,
My first suggestion for your personal visit would be RDG tools. Within easy striking distance from your base.
I would suggest, look on their site to find some of the necessary things you want, then phone them up and place a pick up order a few days before you go. A lot of popular items do go out of stock quickly. Then when you visit, top up your order with goodies as you look around. Tell them you are an overseas visitor and see if you can get a tax break.
http://rdgtools.co.uk/
Another very good supplier, and I think would be well worth a visit, again within striking distance of your base. Very efficient and helpful, plus they do have some things on their site that are not generally available anywhere else, Arc Euro.
Again, because they are so popular, things do go out of stock rather quickly. So maybe a pre placed pick up order would be advised.
http://www.arceurotrade.co.uk/default.aspx
Tracy tools is a place I get all my taps and dies from, even though most are carbon steel, they are very good quality and I have never had cause to fault them. Their full sets are very good value for the money. A bit far for a day out, but maybe get them delivered to your base.
http://www.tracytools.com/index.htm
One place a lot of people don't know about is Gloster Tooling. Very good to deal with, and some of the cheapest prices on the net for certain items. He does offer tax breaks, and is very good to deal with on the phone.
http://www.glostertooling.co.uk/
He also has a very good ebay listing.
http://stores.ebay.co.uk/Gloster-Tooling
Ignore what it says on his downloadable catalogue about 'available 2008', most items are usually in stock.
For materials stock, I always deal with Blackgates, very reasonably priced, good delivery times. Website is a load of crap, so you need to order over the phone.
Maybe a good place to visit when in RDG country. Not too far between the two.
http://www.blackgates.co.uk/body_index.html
Hope this helps.
John