Do you have a certificate of residence or do you mean you have a TM30 filed showing the property owner has registered you as living there? The 2 are not the same thing
What are the ages of both you and your wife? If you are under 50 your visa options are pretty limited. Are all of your kids under 20 and will they be attending school? If your kids attend school on an ED visa then the parents can get guardian visas, but schooling is expensive
as I've said previously the description of work in Thai law is defined very tightly. It would on my view mean that no work is allowed on any visa or no visa. Saying that the Thai government has obviously chosen to make a couple of exceptions
You would be wise to maintain your UK bank accounts and have your pensions paid in there. You also need to inform the state pension people of your Thai address, I had to do that for pension and overseas landlord status but I don't remember having to provide any proof of address. Probably best to call them and explain