The confusion on threads is because people don't specify what they want, BSP is not an accurate description, BSPP (parallel thread) or BSPT (taper thread) makes things easier, BSPP has 2 options for sealing, a tapered seat on the nose of the fitting or a seal on the sholder.
And just to make it interesting the Americans have NPT, it looks very similar to BSPT but has a different thread pitch.
Apologies for the delay in getting back to you, but I just wanted to say that this statement is the single most helpful few words in the entire thread!
Now I know what I'm looking for - many thanks
edit: Everything else was useful, too - just that I now know what my odds and sods connectors are - thanks to everyone else who responded, too