$40k USD is a fine amount of live off of is you are living in Carbondale, IL. But less so Chicago.
It's a pretty decent way to live in Belize or Costa Rica. Good luck in the UK. Germany, probably not, but Czech Republic may well be fine.
It depends on where you want to live. One of the factors which makes a huge difference is how old you are - the older you are the better healthcare you're going to need. Some of those low cost destinations don't have that great of healthcare - but some do!