The following applies in England & Wales, but I believe it applies equally in Scotland (but perhaps someone can correct me if I�m wrong).
First of all, the Association of Chief Police Officers issues guidelines for speeding offences to determine when a fixed penalty should be offered. For offences in a 70mph limit, a fixed penalty is normally offered up to and including 95mph, so there is a strong likelihood that a FP will be offered.
Whatever course of action is taken by the prosecutors they firstly need to establish who was driving and they should ask you this (assuming you are the Registered Keeper) when they serve a Notice of Intended Prosecution (NIP). You are obliged by law to provide these details within 28 days. If you ignore the request (and this includes returning the form incomplete or unsigned) they will not send somebody round to provide a verbal NIP as suggested by north star so you will have no need to avoid opening the front door for six months.
The next thing that will happen is that you will receive a summons for failing to provide the details under Section 172 of the Road Traffic Act. The guidelines for this offence include a fine of one and a half week�s net income and a minimum of six penalty points on conviction. All the prosecution has to do to secure a conviction is to show that they posted a NIP in good time to reach the registered keeper of the vehicle. Unless you can show good reason why it was not received (and the onus will be on you to do so) you face conviction.
Almost all of the alleged loopholes relating to speeding offences detected by camera have been tried and tested, some of them having gone as far as the European Courts. If you were speeding the best thing is to own up, hope you get away with a fixed penalty, or plead guilty if you are summonsed.