Immigration are are already cracking down on 60 day border bouncers. Either get a retirement extension yourself or pay an agent, with money in the bank should be less than 10k. PM me for good agent if you want.
Keep UK bank account open, don't bring all your money over in one go, consider keeping at least some investments in the UK, buying properties for rent in a market you are unfamiliar could be an expensive mistake.
New ETA Electronic Travel Authorisation is being introduced in early 2025, fully by June 25, but delays have already occurred, dates are bound to change.