OK I've found Dave Houstons excellent examples page, now i guess I just need pointing at a suitable pair of modules.

+10dbm is needed for a longer reliable range, the antennas are no problem.

I'm still confused by the choice of module, i suppose I'm saying i'm too dumb to understand the different protocols

Incidentally, the choice of 868MHz was his, apparently the place where this is to be used is full of 433 devices and he wanted to avoid a clash.