My understanding is that the number of points you get will not depend on whether you take the case to court, or not, but the fine and costs could be affected and are likely to be significantly more if you lose. Also consider the cost of taking time of work, which you can't claim back if you win.
Of course if you win you will not get any points, fine or cost against you and you can claim costs, but don't expect too much from that.
If you admit to being the driver you can ask for a copy of video evidence under the Data Protection Act (DPA) prior to expiry of the Fixed Penalty Offer, see my other postings on this. Don't let the police tell you they are exempt from the DPA as I had a ruling from the Information Commissioners Office (ICO) to say they are not. The video, if there is one, may provide some help with determining the conditions, such as whether there were other close vehicles which may have affected the laser speed gun, if that is what they used.
Take a look at the ABD site,
http://www.abd.org.uk/ , as they have quite a lot on signs and markings, particularly for the road.