From Inverness:
Head north over the Kessock Bridge and join the A835 towards Garve/Ullapool. After Garve turn left onto the A832 and follow signs for Gairloch. Turn first left after you enter Gairloch (opposite the Les Buchan DIY Store sign) and follow the road round past Charleston House. Charleston Cottage is facing you in between the posts marked as private. Parking is available by the gate to the house.
Fliying to Inverness is easy from the South. There are flights from Manchester, Bristol and London each day. You can even fly from Southampton via Manchester. There are more regular flights from a more varied number of airports to Edinburgh and Glasgow where a car could be hired. From both of those cities Gairloch is about a 4.5 hour drive (depending on how often you want to stop). The drive is very scenic particularly as you drive through the Highlands and the differing scenery it offers.