If you are a member of a fell club, then you would probably know of some club runner, in your own club or other clubs who have done the B.G.R. and so be able to form a support team of navigators/pacers. and helpers.
If you are not a member of any running club, especially a fell club, then the problem is knowing or finding people who have done the B.G.R. and are willing to help you to form a support team.