Hi and welcome to the Forum.
You shouldn't have a problem; once you are resident (i.e. actually living here) then the NHS is available for you to use. The NHS doesn't cover general Dental care, so you will need to make some provisions for this.
Details on costs can be seen on the Numbeo website; this will take you straight to a costs comparison for Bangor & Swansea. It currently only compares 2 sites at a time, but there is data there for Wrexham as well. The data is generally about 6 months behind the curve, but your pension sounds sufficient to live in Wales.
Speaking some Welsh will help you to integrate should you choose to live in an area where they speak it.
I'd strongly recommend that you visit the areas you are considering moving to before you sell up and move.
Hope this helps.
Cynic
Expat Team