Hi again, Scato,
You've mentioned beaches twice now, so I have to believe that they are of primary interest to you. Scotland is not usually somewhere that you think of for beaches. Most Scots travel to the Mediterranean or the Canaries on their holidays, if they want the beach experience. That said, there are beaches in spades (which you'll need, along with a bucket) on Scotland's coasts.
Some of the best beaches are at Lossiemouth, near Elgin; Newburgh and Balmedie, near Aberdeen; Sandwood Bay, near Kinlochbervie; Big Sand, near Gairloch; Sango Sands, near Durness; Achmelvich, near Lochinver; Tolsta Beach, on Lewis; Luskentyre and Scarista beaches, on Harris; Golspie and Brora beaches, just north of the Dornoch Firth; Camusdarach, near Mallaig; Calgary Bay, on Mull; and Skyegirl has already mentioned Sanna Bay, at the end of the Ardnamurchan Peninsula.
Have you considered breaking up your week of exploration in to two segments? That way, your day trips wouldn't necessarily have to be as lengthy. Perhaps a few days along the Moray coast, then a few days on the west coast. Ullapool would put you within a reasonable drive of Big Sand and Sandwood Bay, as well as Sango Sands. Ullapool is large enough to find shops for your groceries, as well as restaurants, yet small enough to give you that "Highland experience." You could even take a couple of days to ferry over to Stornoway, to explore Tolsta Beach and the South Harris beaches. The choices are limitless (almost).
One possibility would be a self catering cottage on Harris, which would give you access to the beaches, with mountains (well, hills) in the background. There is a good choice of hikes, good food (Scarista, Leverburgh, Tarbert, Scalpay), and even a few pubs.
I hope that you are eventually going to find a solution that works for you.
p.s.: If you end up in Torridon, and self catering, you're going to have to go a long way for messages (groceries). You'd be midway between Lochcarron and Gairloch, both of which have small supermarkets. There is a small shop and cafe in Achnasheen, and a small store connected with the post office in Kinlochewe.