the drivers side engine mount is nackered, Ive got a new one to replace it with but how do i support the engine when i take the mount off.

Car jack and a lump of wood in the right place. Jack it up just enough to take the load off the mount. Unbolt, replace, bolt up, lower away. Keep the old mount for a repair later.

lift the engine just as mad max said but if your worried about it droping, lay a large steel bar between both strut tops and chain the engine up to hight. helps a little bit with safety

Car jack and a lump of wood in the right place. Jack it up just enough to take the load off the mount. Unbolt, replace, bolt up, lower away. Keep the old mount for a repair later.

Which would be the right place?

Make sure you have a breaker bar & cheater extension bar handy at the time. The three bolts that bolt the mount to the engine can be bloody tight. Use anti-seize when you put it back together.
I just used a trolley jack to support the engine.

thanks guys im just about to replace this by self saved me asking

That's by far the easiest mount to replace. Everybody else has explained it pretty spot on. Had to change all 4 on my KF not long ago… what a pain in the ass that was.

so the right place would be the sump??

so the right place would be the sump??
That's what I did.
Trolley jack under the RHS of the sump with a block of wood to spread the load. Your only supporting that side, not taking the full weight of the engine.