You're in the same position as me. Unfortunately unless you can get an Extension based on retirement (in which case your wife can piggyback like she does with your work extension) your options are limited. Do you have children at international school? If so, you might be able to get them an Extension based on studying at school, and piggyback on their extension.
As you're on an Extension of Stay based on work, this will end once you stop work and your WP is cancelled. You will have 7 days to leave. You should be able to change the reason for your extension to marriage, assuming you're married to a Thai and meet the financial conditions. As Billy Brown says, go and talk to your local Immigration office.
Maybe it depends on the Immigration Officer, but I've only ever had one TM30 filed at CW, despite having numerous trips within Thailand and annual extensions since then.