you should receive a notice of intended prosecution within 15 working days taking intpo account weekends and bank holidays, the chances are you will get 3 points and 60 quid fine for dangerous driving, you contest it then you could end up with more points and a larger fine
the 15 days is a guideline and if you receive it a few days after then really you havent got a case, if it turns up like 6 weeks later then i suggest u get legal advice and start sending letters to the courts
courts take a very dim view on drivers who think they are above the law and contest it, unless your missus was giving birth or a relative was seriously ill and dying in ya passenger seat then you havent got a leg to stand on, they will make an example out of you in court and possibly want to charge you with another offense as well as court costs
swallow the fine and points and take it like a man and get on with ya life
i got 11 points from speeding in 30 zones and i contested one of them and they gave me another 2 points and an extra 50 quid fine - trust me it aint worth the stress and hassle, unless your a millionaire with money to waste then dont bother