Wow, sounds exciting! I wouldn't worry too much as you have already done the distance although the West Highland Way is famously hilly so maybe you should enjoy the practice run, and also get out and run a few hilly trail routes over the next couple of weeks.

Just go more slowly!  If you're at a speed where you can talk you should be able to pace yourself for the full leg.  I reckon on being about 30 to 40% slower on really rough/hilly terrain compared to flat roads so if think of it in those kinds of time it might help to make sure you get the right speed for the full leg. You can always speed up towards the end if you have undercooked the speed but if it's the other way round it can get a bit unpleasant! 

Hey Robyn,

I am running the fling, my strategy is always the same as Bratto's.

Since im doing the full thing ill walk the hills (most ultra runners do this) no shame it doing that as the whw is very hilly. What leg are you doing? If the first one then youll be fine, no hills at all more or less.