Make sure you get a good quality T55 torx bit. I went through three or four when I did mine, crappy Halfords standard issue ones. Obviously you will need a torque wrench. It helps if you have a long bar, like a breaker bar, when you do up the headbolts to the right angle. Too short and its bloody hard! If the torx bit does snap, get a magnet in there and get any metal shards out pronto.
To be honest, at this time of year (any time tbh) it's a shit job, but it will give you the chance to really give stuff a good going over, not just the HG.
Be careful lifting the cylinder head out with manifolds attached, without assistance! I hurt my back bad doing that
Dont get ripped off sending the head away to be lapped and seals done. I did. It was a good job, but they way overcharged me at the last minute. Simple compression testing and skimming should not cost much.
When you lower the head back onto the block, be careful you line it up. It would be easy to put some nice big scratches in the nice new skimmed head surface.
Make sure the 2 locating dremels are set properly before lowering head onto block.
Remember to tighten the cambelt correctly
Finally, don't turn the car over via started motor until you have hand cranked the engine fully to check valve clearances.
Have fun!