Hello,
It sounds like we're in similar situations. I'm also in the UK, my accident was in January so I'm about 9 months in with similar symptoms to you.

I only just got referred to the right person, it's taken months and months of arguing with my GP who kept telling me it was anxiety/depression/PTSD.

I'm in the process of a claim and through that I saw a psychiatrist, who said my symptoms were not in line with anxiety/depression and he recommended a referral to a neuropsychologist.

I took that report to my GP who finally referred me and long long story short I've had to be re referred but I'm now finally heading in the right direction.
I'm waiting for my referral letter but I should be having a cognitive assessment in the next 6 weeks.

I'm in contact with headway, they've been really helpful, sent me some fantastic leaflets, they're trying to get me referred for therapy, they're going to help me with my application for benefits etc.

I strongly suggest contacting them, it was enormously helpful just to vent to them and know I was talking to someone who gets it.

I'd be more than happy to chat if you'd like some support, I think it would help me too.
I'll PM you

Abbi x