Your local motor factors will be able to supply you with the correct NGK ones mate, I think mine were about £11 or £12 each iirc.
Ye same mate, 3 times! I had some shitty Beru's in mine and it took 3 glows in cold weather now with the NGK's I dont even have to wait for the glow light to go out.
These engines are notorious for misfiring when started cold till you tickle the throttle a wee bit ;P