The Cycle Touring Club (ctc.org.uk) has three well-established routes and other information for members that can be downloaded from its website. The YHA (yha.org.uk) and the Scottish YHA (syha.org.uk) have a 16-day route between their hostels, which you can download. Book two to three weeks in advance as certain hostels, like those in the Lake District if you plan to tackle the Kirkstone Pass, get very busy. Also worth stopping at Carbisdale Castle SYHA, north of Inverness, possibly the best hostel in the world.