Brilliant and thank you to everyone ... that's really useful feedback and I must admit fits in with how I feel
The Mrs asked if I fancied doing the ride and my instant response was I really don't fancy the fundraising bit and asking friends for money and everything that's been said in here pretty much re-iterates the same.
If you were to enter one that was a reasonable cost, what would you want from it in terms of the ride / distance, I'm guessing a "scenic" route might help but probably not the deciding factor ... what else would you like that'd make you say I fancy doing that??