Have a look on this thread for an idea of half and full distance races next year.
2026 Half & Full UK Ironman events - Events - TriTalk.co.uk
I liked the slateman standard when I did it 8 years ago but the water can be chilly. Plenty of other options but the Outlaw half isn’t far from you.
Obviously the likes of Bolton which is a tough course but not cheap either. For Wales you really need long hilly rides