He was not in the wrong. You are!
The highway-code states you should only pull out when its clear and safe to do so and you won't cause other drivers to have to slow down.
Your a new driver, let this be a lesson because the next time the person you pull out on might not have quick enough reactions to slow down in time and he will either t-bone you or drive right up your chuff.
Only pull out if you can do so with effecting anyone elses driving, so what if he is speeding, you are not the law, if he wants to speed he can do so, does not make it right for you to pull out and possibly cause an accident.
... Not always possible though is it.
I'm sure the highway code mentions something about speed limits too.