Good luck Hamish. My wife Helena and I did the ride about six years ago and it was fantastic. But we took our time, zig zagging for seven weeks, plus another week riding around Orkney. Then it was a ferry to Aberdeen and cycle to Edinbugh before flying back to Australia. We stayed at 39 different YHAs most of the way including a few places you mention - Perranporth, Cheddar (cycling up the gorge is a delight!,)Tiverton and Bonar Bridge - where we stayed at nearby Carbisdale Castle. From Bonar Bridge we went up to Helmsdale and then inland and round to Thurso - one of the best stretches of the ride - before Jo'G. You are going the best way too - generally you have a tailwind South to North. On the music side I found some of the YHAs had people staying there with guitars and we had a few good music nights along the way. Good luck and let us all know how you got on.