There was only really one dealer anywhere that sells multiple brands of Ti bike which was Fatbirds/Pedal Revolution in Kings Lynn, now sadly closed down
Enigma have outlets around the country
https://www.enigmabikes.com/pages/dealers but they're not specifically tourers but they have a range (their frames start at £3k up IIRC)
You'd be much better just to head to Spa cycles, the shop is very near to a train station with connections from York or Leeds if not driving. They have a few Ti options, Spa and the Sabbath brand which they now own. Just call in advance to check they have the bikes you want in your size to try, they're not open on Sunday IIRC.
I spent months looking at Ti bikes, I went to Enigma in Sussex, I went to the place in Kings Lynn, to Reilly in Brighton, I tried a J Guillem locally, looked at Pearsons, checked out PX, Dolan as above.
Settled on the Sabbath AR1 as the best value for money and completely customisable, notably I didn't have to have a Shimano groupset, yet more 42cm+ bars that are too wide, or black bartape (I supplied purple to Spa and they added the purple cable outers), I didn't have to pay for a saddle I didn't want and could have handbuilt wheels with a decent number of spokes!
What's your total budget for the bike? Back in 2016, Spa were really the only ones with a bike that I could completely custom spec with SRAM, handbuilts etc under about £4k.
Sonder (Alpkit) also have fairly reasonably priced Ti bikes but they're availability can be a bit hit and miss).
eg the Colibri road
https://alpkit.com/collections/sonder-colibri or the Gravel Sedona
https://alpkit.com/collections/sonder-sedona-titanium-gravel-race-bike
There's an Alpkit shop in Edinburgh and Inverness
https://alpkit.com/pages/stores? Obviously call before travelling
