Is there a digital product that allows printing of (parts of) UK charts?
Yes,
http://shop.memory-map.co.uk/acatalo...00_Charts.html. The maps are printed at the scale you want, so a 1:500,000 is the same as a printed CAA chart. You can mark your route on the map and, if a SkyDemon user, import your route from SD. The route will be overlaid on the printed copy.