sorry for such a late reply. From disposable pet prices to rarer than hens teeth in just a few years!!
Obviously keep an eye out on the main UK online suppliers, thespidershop and bugzuk. If you have facebook, then you should join as many sales groups as you can. For a start there's Inverts For Sale UK. ReptileForumsUK has a classifieds section that can be worth keeping an eye on.
You'll probably have better luck sourcing them from Germany/rest of Europe as scorpion keeping and breeding is much more popular there. http://www.terraristik.com is a classifieds site that lots of breeders use. Again, facebook, you could join the German ''Skorpione BIETE/SUCHE'' group. There's also a number of European breeders who have their own websites; http://buthidae.ch/, http://buthidae.eu/, http://www.polyped.de/, there's others but I can't remember their web address. Finally there's a couple of forums with good classifieds sections http://www.skorpione.de/forum/viewforum.php?f=8&sid=ad1206daac85396e9afc277f495d9f0e and https://www.skorpionforum.com/forum/33-biete-nachzucht/?s=75d72643ddc1f65b3d33d7cb28727e52246aa6e9.
Lastly, you're in the South East so you could pay a visit to the SEAS Invert Show at the end of the month http://www.invicta-arachnid-club.co.uk/index.php?slab=s.e.a.s.
This species is being bred in captivity, just shamefully few compared to how many 1000's were imported and sold for pennies before, eventually I think you'll find some, but they may end up being juveniles.