From the bit of research I have done I have found this: If, as an overstayer, you make an application to extend your stay whilst in the UK, then unless you make this application within 28 days of becoming an overstayer, you will face a mandatory refusal. The Home Office will disregard the first 28 days as an overstayer, although remember you have to rely here on the Home Office getting the decision making right first time round as there is no appeal right to the Tribunal.
For those who opt to return to their home country, they must ensure that they do so within 90 days of becoming an overstayer otherwise they too will face a mandatory refusal, subject to certain exceptions.
So, in short the lesson from all of the above is to avoid at all costs becoming an overstayer. If, however, you find yourself in this position, then do seek urgent legal advice and remember the 28 and 90 day time-scales above.
As our wise KFDancer has advised, you should honestly get yourself a very good human rights lawyer as 8 years is a very long time. Do you have children that you could base your argument off of?