There are currently no outbound requirements (though it’s a valid question, as only a couple of months ago Thailand had some mind boggling stupid rules that were conditional upon the requirements in the next country you were travelling to).
You’ll have 6 months validity remaining when you check in to travel TO Thailand, so you’ll be good for that sector. If your return sector is directly from Thailand to your home (passport issuing) country, you should be OK, however if you’re flying via anywhere else, that respective country may not permit you to travel. I would recommend caution, and renew your passport. You could also check with your chosen airline. Good luck.
So sorry for your loss Tony. You did the best you can, so try not to beat yourself up. On your question regarding being better off in Thailand … this country, while it does have excellent medical facilities, is extremely slow. Given the cultural aversion to bad news, windows of opportunity are often missed. So, no.