My experience suggests the Switchover will improve things. I don't have a clear view of the nearby Belmont transmitter; like most of the village, we have to point our aerials at Emley Moor. The power increase meant that we could stop using aerial amplifiers, and we were also getting a strong enough signal from Belmont, about 100 degrees off-axis to be get viewable oictures. So it might be worth the wait for you.
Doesn't matter which ISP you're with, it's the strand of copper between you and the exchange which is the key. Your's sounds pretty decent. Maybe the evening choke-off will ease, as capacity is added to cope with YouView. I'm not sure I want any more TV, but will I have to subscribe to be able to get useful bandwidth?
I have some "hard" questions which the sales-droids never seem able to answer. That could easily be another, but since they will be advertising the hell out of YouView, I doubt it will be as difficult as learning whether there are plans for IPv6