No, weirdly, I can't seem to see any for sale here.
I might get a couple of cans of the aerosol when I go to England and bring it back on the plane.
I don't think I can be bothered to flush the system and clean it, as I hosed out the radiators when I hooked up the pipes a few months ago. It's been sucking in air though and I think I've found a dodgy automatic vent, so I'll fix that tomorrow.