100m would be enough distance to pull out and take the turn if the bike was traveling at 60mph, the limit. The driver has no reason to assume the bike is doing 100mph.
I've already given some calculations which show you're wrong;
100m takes 2.3 seconds to cover at 97mph, 3.8 seconds at 60mph
The car cuts across the give way line less than 2.5 seconds before impact (so bike would be approx 100m away), and would have taken more than 1.5 seconds further to clear the carriageway.
Therefore, even at 60mph for the bike, the car would still be in the carriageway. Bike would have been able to avoid the tail of the car, but the car should never have started the manoeuvre - it was simply dangerous