There are hotels, guest houses, hostels, and camping sites dotted all along the way in Scotland. If you are going during the summer, then sleeping in tents is a great option. In Scotland, by the way, it is perfectly legal to camp anywhere you please. On the official website of Scotland's tourist office there are a few rules that all lovers of a cool morning in a tent should follow. Among them, the most important are: take all your rubbish with you, do not leave traces of fires, etc. The rest is complete freedom.
If you like comfort, then there are dozens of accommodation options with different price ranges: from 10 to 350 pounds per night. You can book directly on Scotland's tourism site.