As UK is out of the EU some reciprocating agreements are no longer in place.
I am a UK citizen and before Brexit Eire had a visa waiver scheme for Thailand nationals that had a UK visit visa. Which was great as France declined a visit visa so we spent a week traveling around Eire and very nice to it was.
you will have a 6 month grace period out of the kingdom so will not look too suspicious. It's when is back to back year in and year it raises a flag if an immigration officer is not feeling the love on that day.
Bear in mind the 60+30 can change at any time. It was a post COVID sweetener to get people into the Kingdom. It's now helping Russian men not having to go back to Russia. It's drives more tourist $ into the economy so always a balance. Retirement visa if you can meet the criteria is the way to go. You can get a bank account and other bits sorted.
Remember to take your boarding pass off the plane with you. It's an immigration requirement to have it available for inspection but I've yet been asked to show it