Thanks, everyone!
Mark - I've grown HC in numerous set-ups and the best tip I can give is to provide plenty of circulation and nutrients, either via substrate or water column, or ideally both. CO2 isn't essential (liquid carbon is a viable alternative) but it will improve growth rates. It seems to thrive with high nitrogen in particular, in case provided by ADA Aqua Soil and my tap water.
I planted just three pots of HC in this, but split them up into individual stems. The stems grow a little leggy at first but pruning them back to near the substrate promotes carpeting. You can re-plant the cutting, of course.
Others have success planting using the 'Tropica' method of splitting pots into clumps and burying them into the substrate with some of the portion protruding. This works well too, but you'll need more pots to get the desired effect and carpeting will take longer. This method is much less labour intensive though...
It's odd that some many UKAPS members have had issues with HC lately, even though they are apparently following the 'correct' guidelines. I do think I am very lucky with my tap water, although I still have trouble growing moss!
Amy - I know exactly what you mean. This tank is in my kitchen/diner and that's exactly what I did!
Thanks, again!