I don't know about Hua Hin but Vantage Siam in BKK offer possible Level A1 packages for UK settlement visa applications using the Cambridge Key English Test (KET).
Here's a link which should start you off:
And here are the costs:
The cost of the computer-based KET test is 5,995 Baht.
Vantage Siam used to offer the BULATS test for UK settlement applications but have now switched to KET as the BULATS test is no longer recognised by UKVI.