This is what I've done so far:
1. Follow the heel turn instructions "sl1, p to gap, p2tog, turn" etc. The purl two together stitch combines the first two stitches after the gap. This gives a nice semi-circular heel but 21 stitches, not the 11 they say you should have.
2. Undo the heel and follow the pattern again, this time combining one stitch from each side of the gap, therefore having 11 central stitches throughout the heel. Barely get halfway through this and decided that surely a square heel isn't right either (I think that move in itself was the fatal one).
3. Undo the heel turn again and set off as before. Turn the heel in a nice smooth curve but end up with too many stitches.
4. Continue with the gusset and do extra decreases until I'm back to how many I should have. Proceed with the foot.
5. When most of the foot is done try the sock on and realise that there is a flap of fabric on the sole caused by those extra stitches.
6. Attempt to remain vaguely calm as I rip back several evenings work. Fail.
7. Try the square heel version again. Follow it through to completion this time and decide its quite nice really.
8. Finally finish sock one.
9. Start all over again with sock 2, skipping steps 1-6. Hopefully.
Lesson learnt? I'd like to think so but I'm not optimistic!