George, I hope you and others find this useful.
Fuel:
Inverness: Tesco Extra superstore, just to the east of Inverness on the A96, has 5-star fuel. Much cheaper here than anywhere further north. It is best to fill your tank here.
Ullapool: The JET Fuel Stop on the South entrance/exit to Ullapool has 5-star fuel (adj the Royal Hotel). NB: Enter the forecourt heading south and take the left-hand side pump set, pump 5, as our Porsche cars have their fuel tank caps on the RHS. It is also a bit tight to get to the left-hand pump set.
Wick: Tesco superstore, west of Wick on A99, has 5-star fuel.
Food: Best savoury and fruit pies are to be had at the Lochinver Larder.
https://www.lochinverlarder.com/ Sitting outside and takeaways during this time of the pandemic.
If heading North from Ullapool turn off the A835 onto the unmarked road (with passing places) towards Achiltibuie past Stac Pollaidh mountain and turn right onto the unmarked road to Lochinver. Obviously, this road should also be taken if travelling anticlockwise and heading South to Ullapool. As a deviation, there are some B&B's and the Summer Isles Hotel in Achiltibuie.
Next, don't miss travelling along the B869 from Lochinver to Unapool or vice versa. It's a fantastic road with spectacular views and passing places on route. Stop at the Drumbeg Viewpoint for more spectacular views North.
Durness: Don't miss the Smoo Cave or Balnakeil Beach. If you are a lover of Chocolate, and all things made with the stuff, the Cocoa Mountain Cafe (
https://www.cocoamountain.co.uk/) is the place to go just before heading to Balnakeil beach. There is also another viewpoint at Sango Bay in Durness village near the camping ground. Park at Sango Sands Oasis Restaurant & Bar area and walk out to the point to the North.
Applecross: Most people stop off at the famous Applecross Inn for a break and good views. There are two options if it is too busy here. The Applecross Walled Garden is a good alternative for delicious food.
Torridon: Apart from the obvious Torridon Hotel on the A896 there is a good stop off with fresh homemade food to be had at the Wee Whistle Stop Cafe, Torridon that is adjoining the Loch Torridon Community Centre. It has indoor and outdoor seating with splendid views across the sea loch and mountains beyond. Find it on Facebook or Google Maps.
Breakdown and Recovery: Limited to possible help at Ullapool, Thurso, Wick and down the East Coast at Golspie. Once you are on route you are on your own. Remember, cell phone coverage is very limited between major villages. Being insured with a breakdown recovery service would be very wise.
Alternative route: If you have covered the NC500 route before there is a smaller but equally spectacular route that takes in the central area of Northern Scotland. Also, as most traffic will be on the very popular NC 500 this alternative route will have little traffic on it. Go from Lairg up to Altnahara (A836) and turn off onto a very minor, single-track road marked "Hope" that takes you directly past Ben Hope and back onto the main road A838 at Hope. Turn left and go to Durness. At Laxford Bridge turn left keeping on the A838 all the way back to Lairg.
TIP: From my experiences on the NC500 (I hate that term) it is best to travel in an anticlockwise direction. This, for me, lets you take in the mountain scenery and seascapes that get better and better as the trip progresses.