I was out early this morning doing some of the big hills, bit of a suicidal day with dog walkers walking in front of me without looking behind, nearly had a head on collision with some tourers who were coming round a blind corner on my side of the road, and then came head to head round a 90 degree blind bend with a group racing each other, most got back onto there own side of the road apart from one half wit who was too busy looking down at his gears, on my side of the road as I hurtled down the hill braking hard, and screaming at him to look up, and his colleagues too shouting at him, only just avoided him by having to go onto the grass, and all I got from him as we passed was a "Sorry mate" as he looked up to see me, we was only about 3 or 4 wheel lengths apart before we would have collided so I was lucky to have slowed down enough, from 26mph to 11mph to dare leave the road.
Hulver, I think you will struggle on a fixed, Nunburnholme's gradient is not signposted, but I think its about 14 - 15% and just under a mile long, and comes after about 43 miles when its starting to get tiring, as for all the other hills, I cannot remember, but Nunburnholme is the worst.
And Nunburnholme on a double is hard, I just creep up on it at 4mph