I've been asking around and I have been quoted in excess of £4k for adult braces. Apparently, braces are ore expensive than Invisalign, which are just cosmetic braces.
I'm in Brum, btw. Willing to go abroad if necessary and worth it.
I have read that Italians go to Croatia to fix their teeth and it shouldn't cost much more travelling to Croatia from here, but I'd not where to start.