The following web page gives you the 'legal' stance on what you can and cannot do:
http://www.cps.gov.uk/publications/prose...lders.html
This is the standard to which your actions will be considered.
As others have said, if you use reasonable force 'inside' your home to protect yourself from intruders, you will not be prosecuted.
There have been plenty of recent cases where householders have not been prosecuted and very few cases where they have been prosecuted, all of which have been where the householders have used grossly disproportionate force. If anything the law protecting the householder has been significantly reinforced since the Tony Martin incident.