I have experience of several weeks of marine operations in this area, but not in my Swallow...rather larger commercial stuff.
We were working off the beach at Sanna for some of the time. Visited several sites ashore on N side of Ardnamurchan both by road (Ft William > 2hrs, probably closer to 3hrs if towing!) and by sea.
It is isolated! REALLY ISOLATED!
I don't recall any slipways on N shore, but the locals launched swallow-size boats off various beaches; Beau Fascadale, I think? Suspect you need a very good 4x4 (preferably a tractor?), and local contacts though?
I recall several slipways on S side, probably at Kilchoan, where the ferry lands; however Ardnamurchan point, where the light house is, is perhaps not somewhere I'd want to visit in my Swallow in anything other than ideal conditions. Very few places to land, let alone run to shelter.
Absolutely stunningly beautiful area (and no midges the summer I was there) - but then you probably don't need me to tell you that! We were regularly visited by Dolphins/porpoises, whales, sea otters and even several sea eagles were seen fishing.
Crystal clear water, sometimes to > 30ft depth, white sand etc...
N coast here can quickly become very exposed, with very few places to shelter on main land side. We ran over to the lee of Eigg a few times I recall?
We worked out of Mallaig on a daily basis, using a fast crew boat; still a long trip.
Mallaig itself not recommended, for many reasons that I will not go in to on public forum. However, it is after all mainly a ferry port...a good base, a place to set off from perhaps? Certainly accessible slips and parking etc there but I recall regularly getting fleeced by various locals for dubious "services" (and I'm from Cornwall, so am used to that approach to visitors!).
Added.
I do know Armadale, on Skye itself. The opposite end of the Mallaig ferry, is very nice and has slipways , sheltered small craft moorings etc.
Maybe a local will be along to help in a minute? Or maybe try the Drascombe forum? I think they have a lot of knowledge of this area.
Hope this is of some help?
Where are you based normally?