Will my plans to visit Thailand multiple times a year on tourist visas work for me?

You can get a retirement Visathrough an agent and it will cost about 20,000 up front. No cash in bank and no problems. Just find a good agent. Cheaper than airfares.

My neighbor goes back to Hull ever 3 months to get another non-o visa snd has been doing this for years

A tourist visa from the UK gives you 60 days on entry, which you can extend in country for a further 30 days. There is no limit to the number of visas you can obtain per year. Where most people have issues is when they are using a tourist visa (or exempt) to live here. After a while the immigration officer will question why they don’t have a correct visa for their visit. Coming 3 or 4 times a year shouldn’t pose a problem. At 73 I’m guessing they won’t think you’re trying to work in the country. The amount you spend is also irrelevant. Enjoy your time here.