Book yourself a Bargain Berth on the Caledonian Sleeper from London, and you can get to or from Inverness for only £19. And Inverness station seems positive about cycling: the first sign you see as you get your bike off the train (right) informs you of the possibilities. (Anyone know of other stations with similar signs?)
It provides plenty of bike parking for employees, too - but it's an amusing object lesson in what not to do. The racks provided are all wheelbenders, right out of a 1970s bike shed. Every single cyclist had sensibly ignored them and just locked up to the railings instead (right).
(Whoever runs the bike parking at Inverness should check out David Hembrow's posts on cycle parking, and maybe hop across to the Neths for a factfinding tour. And they can get down to London and Eurostar for only £19...)