Ullapool is a good place to head for but it would be a shame to go all that distance and then turn around and go south.
Try this..
Hit your nearest motorway(M6,M74,M8,M898), select warp drive and get on the A82 at Dumbarton , petrol and Little Chef, Tarbet, A82 biker friendley pub at Inveruglas (I think), Crianlarich, Tyndrum for the biker friendly Green Wellie shop, A82 to Fort William (lots of B&B), Invergarry(petrol), A87 to Shiel Bridge (cafe at first filling station), on to Kyle of Lochalsh for rest, A890 to Stromeferry (divert through Plockton for sceanary to keep wife happy), on to Lochcarron o A896 to Kishorn. now go on the unclassified road to Applecross (hairpins) on continue around to Shieldaig,Torridon (Ben Damph hotel for good grub),B&B at Mrs McKay 01445791333 ask for room with view), Kinlochewe (resist hunger - dont stop here), A832 to Gairloch, A835 to Ullapool, B&B, A835,A837 to Inchnadamph, A837 to Stoer, round the coast and back north on A894 to Laxfor bridge, A838 to Durness (B&B first on left), A838 to Tongue, Bettyhil (most expensive petrol - ever) go to cafe/Fish'n'Chip resturant, Thurso, A836 John O'groats, A9 to Wick, Helmsdale (hairpins),Tain,Carrbridge (B&B), A938 to Grantown, A939 to Tomintoul, Breamar, A93 Blairgowrie, Perth, Then back home, keep off warp drive on A9, keep compass to south and hit warp drive again. Take midge repelant!
Was that toooo much detail?