Hi Laura, I did the TT last year. Its pretty consistent in terms of terrain, so no drier in the first half compared to the second tbh. I thought it was mostly flat. For what its worth, the bits to keep an eye out for are (going by their map you can download):
(1) page 9, about 30miles, theres quite a steep track/hill - not what I was expecting from a river path! So will be a lot of walking for that bit
(2) page 10, I almost missed the point where I had to come off the river way and start heading into CP4
(3) I (and a couple of others found the signage after CP4 very bad round the housing and it slowed us down a bit. Once we got back to the river it was fine so worth studying up before hand
(4) By the time we got to about 45miles (I think), near Mill Lane I think (page 13), it was very dark and we took a wrong turn in a field of sorts. Realised we had gone wrong when the path took us to a locked gate we would have had to climb (you dont climb gates), but the sign was obscured I think by the snow. Anyway another watch out
(5) I was bloody fed up of fruitcake by CP4 and was disappointed that at the end most of the stuff was gone/depleted and I was reduced to a cup of tea and more fruitcake!! [BTW I really like fruitcake and it was a nice recipe but .... well you'll get what I mean when you do it]
Apart from that, I quite liked the race, the organisers seemed friendly and it has the potential of being a fast one (if you get through the hilly middle). Was thinking of doing again as a training run for the TP100 6 weeks later.