@Simon ****
you will have to leave Thailand to get the Non O Visa as a TRAILING SPOUSE... issued by the Thai Embassy in Penang.(as it's known to issue it).
Then go to your local Thai Immigration office to get the One year extension of stay as Married and as TRAILING SPOUSE with your ending date of stay to match that of your spouses.
There are other posts on the forum about the TRAILING SPOUSE.
Use the search 🔍 tool top of the forum page
ENTER the words TRAILING SPOUSE
CLICK on it and all posts about it will pop up to read the posts and replies of others.
Your question about the marriage certificate is a good One.... let's see what others reply.