Haven't moved to Thailand yet, just attempting to beat my tourist Thai into reasonable shape to get a head start.

I'm browsing various learn-Thai youtube vids at the moment and most of the Thai instructors pronounce j/ch as 'ts' which I hadn't actually heard/noticed before, though I guess I have been overreliant on one source for learning. Is this a regional thing? Or standard/Bangkok Thai?

There are only two affricate consonant sounds in Thai - unvoiced/unaspirated and unvoiced/aspirated. Different transcription systems use different symbols to represent these sounds, but the sounds don't change.

You may read a nice description here.