Excellent stuff, Nareloc. Brings back the memories from last year when I cycled from Carlisle to Fort William and went via Arran, Mull of Kintyre and Inverary.
I think fate did you a favour, in one sense, by forcing you to ditch the detour to Mull of Kintyre: it's a very tough ride, both the section to Campbeltown and the next section from there to Mull of Kintyre. I saw the lighthouse but decided not to waste time descending 300m to get next to it! The weather prevented me seeing any further than about 400m out to sea, so no chance of seeing Ireland.
And you're quite right about not having to spend much or go too far to have an adventure on a bike tour. Where are you going to next?