Speeding is a 'summary only' offence, meaning that it can only be dealt with by a magistrates' court, not by a Crown Court.
For such offences 'information must be laid' before a court within 6 months of the offence, otherwise no prosecution can be allowed. So the Crown Prosecution Service have got a couple of months left to issue a summons.
Assuming that you were in a 70mph zone (rather than, say, a 30mph one), expect a fine equal to about one and a half times your weekly take home pay and 6 points on your licence. (A short ban, between 7 and 56 days, could be imposed instead of the points though).