The speed will not be taken into account as cannot be proven either way. This could be considered as dangerous driving (imagine if it was rush hour or there were children in the car) which carries points and a fine. I hope you have good insurance
Proof isn't important when the other driver admitted to be speeding. The speed is also of importance as there is a bridge and a corner approaching the junction from his direction.
Either you're not in the UK, or you don't really understand how insurance/driving law works here. Accidents are a civil matter, unless injuries/death are caused. The police don't get involved.