I was waiting at a junction to turn left onto a main road and as the car approaching me from my right was indicating left and he had appeared to slow down I assumed he was turning into the road which I was coming out of. Well he didn’t turn left and as I pulled out he knocked me off my bike fracturing my ankle and dislocating my shoulder. His insurers are claiming that it is 50% my fault. Is this correct?
There is quite a lot of case law in these circumstances. The case of Wadsworth v Gillespie was similar to your accident. The court held that the person on the main road (W) was unaware that he had accidentally knocked the lever of his indicator. The court said that the person pulling out (G) failed in her duty in not taking a further look to satisfy herself that W was indeed turning left. The court also found that W failed in his duty of care as he was proceeding along a main road giving a misleading signal. Liability was apportioned 2/3 against G and 1/3 against W.
But, the case of Winter v Cotton is closer to the facts of your accident as that involved a slowing down vehicle that was indicating, like in your case. W relied on both the signal and C's slow speed and the court decided that C was 100% responsible.
The Highway Code makes it clear that a driver on a main road has right of way but the court will look at all the circumstances surrounding the accident including signalling, behaviour and witness evidence. The advice to those emerging from minor roads is to wait and only do so when you are 100% sure it is safe to pull out.
You should press for 100% of your compensation for injuries and financial losses based on Winter v Cotton but do be prepared to accept a reasonable offer bearing in mind the ever present litigation risk.