Highway code rule H1 covers priority of road users. Is she at fault for not looking yes, but if it came to a claim or the police were involved for what ever reason, the bike rider would 100% be at fault.
H1 doesn't work like you seem to think it does. It doesn't absolve you of responsibility for your own actions or inactions.
Other posters are also correct in that 'accidents' are vanishingly rare. Both parties could have done this differently, and the biker can no doubt learn some lessons for the future. That doesn't make him in any way liable, however.
BTW, you're not the only one who drives/rides like that, I'm an advanced course instructor... That doesn't mean the woman isn't at fault here.