Bren, I would highly suggest that you get your retirement / multy entry visa in your home country prior to arrival in Thailand this way your ready to enjoy the country and what it has to offer. The renewal process after your first year is very easy. If you are on a pension this can be used for proof of income or your bank account in home country (if applying in home country). This way you will not need to as they say here"border hop" to get visa's
Good Luck