In reply to DaveHK:
Seems like some good advice on the thread, Dave. I've only done the BGR so no expert but obviously going to try for RR also. From limited experience on the BG I'd say the 3 things to make sure you do or don't do would be:
Hills - lots of them. I think you can tick that one off already.
Get your head in to night running. Probably a bit more than setting off for an early start in winter. I was warned before not to underestimate this one and in hindsight it was very good advice. Go out for at least a couple of long night training runs. Start at 9 or 10 and run through till 5 or 6 sort of thing.
Don't get injured through over doing it. In the end my BG training became a bit of a balancing act between making sure I had enough miles in me and managing the inevitable injuries as I picked them up.
Make sure you have enough pick me ups between the legs - people, brews, selection of food to choose from, whatever..
And definitely be prepared in your head for stuff to go wrong. I was utterly set on getting a sub 20hour BG but on the day was very happy with 23h. I had a nightmare on the first 2 legs, which I had expected to go like clockwork (i.e. underestimated). BY the time I was at Dunmail Raise my morale was in tatters - I was very lucky to have some good people around me to get me going again.
Gimme a shout for some training runs. Free this weekend if you're keen.