as above, there are not 'HT' leads as such. If you look at the top of the engine there are 4 black plastic squares, which is the top of the coil packs. These plig directly onto the top of the spark plugs and are about 10" long?
They are about £30 each from a dealer, BOSCH is the OEM manufacturer mostly, although there are other makes.
There has been a number of recalls across the VAG range, VW and audi years ago, seat seem to have finally done the same on some batches.
GSF, and popular internet auction sites sell coil packs cheaper, but id stear clear of ordering off the net myself as many dont work if chucked about or fail quickly, much better to have somewhere you can visit to get a replacement.
If your are working, then id say get a spare one and keep it in the car. If they fail you will typically get a very rough misfiring engine, - and also likely to get a engine warning light.
Clearly there are wires which run to the coil packs, but these are not HT leads and simply plug into the top of the coil pack. if you change a coil pack take time and be careful with the wires so as not to damage them or the plug clips.