Where is the best place to do a health check for retirement visa? Location and costs

Planning on a short trip to meet up with my thai partner for only a few weeks then return to uk. My plan is to apply early next year for a retirement visa!

Should I apply for a tourist visa initially and apply for a bank account during my stay in preparation.

Or

Start the process of applying for a retirement visa. (From the uk?)

Single entry but then would need to get a re-entry permit before leaving.

Or Multi-entry?

I have the available funds but would need a health check and police check which from previous posts it sounds easier to apply for in Thailand.

Any advice welcome!