Did this a few years ago. The first couple of miles are fairly built up, but doesn't take long to get out of Glasgow and most of the rest is rural apart from the last few into Auld Reekie. The only climb on the route is at the Falkirk wheel. Have a torch handy as there are a couple of dimly lit tunnels, there are also a couple of high viaducts to be aware of if you don't like heights.
It was well organised and the aid stations are well stocked. The finish line was right next to a bar for refreshments
Last year I used a Montane Lite-Speed H20 which is waterproof and has taped seams, very light weight and rolls up very small. Seemed to work a charm even in the driving sleet. Cost me £45 from SportsShoes, I think it may have been discontinued but there are still some around for bargain prices, beware though that it has to be the H20 model as the standard Lite-Speed is not waterproof and doesn't have taped seams.
I find running up and down hills uses my muscles quite differently to running on the flat. The uphills stress my glutes, the downhills my quads. If you are planning on a hilly race then hit the hills in training. I would probably mix it up between a few long reps and many short reps.
I don't know the route of the White Cliffs run, but it is likely none of the hills will be huge, but it will be constantly up/down/up/down and some of them will be steep which can make it difficult to get into a rhythm. When I did the Jurassic Coast a few years ago I used the steep hills as an excuse to walk.