@Norman ******
, get a 90 day single entry Non-O visa based on marriage to a thai from the UK before you wing your way here, then get the 400K baht financials sorted out here and get a year extension based on marriage from the immigration office when you have 30 days or less left on that 90 day entry stamp from the Non-O visa. That would be the easiest thing for you to do.
The rest of your plans are just that, plans that may or may not work out BUT seeing as you've been married for 5 years a Non-O and then an extension based on marriage seen to be a pretty safe bet