Get the housemaster of the tabien bahn you husband is registered in to photocopy the first page and pages with husband's name ,stating they allow you to live there. Make sure house master signs it. Take that and the actual tabien bahn to immigration when you apply . Also a signed copy of both sides of housemasters thai ID card. You will have to apply at the provincial office of said tabien bahn.
. You only do a 90 day report if you stay INSIDE Thailand for MORE than 90 days. Only done on yearly extensions. Spouse VISAS only allow you to stay max of 90 days and you must leave and re ente. This is all stated clearly by immigration on websites, etc. If you're still confused , ask them directly in person. Any embassy or consulate outside Thailand that gives you a visa will explain this to you. They won't discuss extensions because it has nothing to do with them because extensions are granted INSIDE Thailand by a separate entity ( thai imm is a branch of the RTP)
. You still seem confused bout the difference between a visa and a visa extension. Only people on yearly extensions need to report every 90 days if they don't leave thailand . Visa holders don't repot because they can't stay longer than 90 days at a time...
If you don't want to spend money on a vacation to do it, you can fly out to any other country and fly backin same day , as long as you officially enter the country you go to (through passport control) . Pick a country that you don't need a visa for though.
. . If the UK is the same as Australia, pensions and superannuation funds are protected because of standing tax laws between both countries. These "new " tax laws are nothing more than proposals at the moment and will have a much bigger impact on thais earning income and holding business interests overseas, which once the elite here realise, will be quickly shelved, like most of the bright ideas the govt here have..
Just guessing that money isn't an issue for you as your only real option as a young family to live here is elite visas unless working here is involved, which could effect your choice anyway. Why don't you spend 6-12 months living in both before making a long term home decision? Also unless one of you is Thai, owning a home/land here is near impossible. Big step without doing a lot of homework outside of Facebook.