As has been said already, we have no castle law. we can barely remove a burgular from our homes without being arrested for assult. Alot of cases have proved even when the burgular hurts him/herself upon breaking into your house you are held liable to any inujuries they may have recieve. hence why barbed wire isn't allowed and why we can't fight a burgular away to protect our families unless he/she is trying to kill you i.e 'reasonable force' however this is also down to interpretation and thus confusion.
A conversation with a policeman after an incident at a property that was broken into and robbed the friendly copper told me 'if the burgular waves a big stick at you, you can wave a big one at him' meaning you can only do to them what they are trying to do to you otherwise it can be deemed excessive or unnecessary force i.e 'assualt'.
I'm sorry but a lot of what you say here is just not true. The media is responsible, particularly the Daily Mail, for this kind of spin on reporting of incidents which has created something of an urban myth. Of course you can use force to defend yourself, your property and other people and it can be lethal if necessary. What you cant do is shoot somebody in the back when they are running away (Tony Martin), or chase a burglar down the street with a Cricket bat, corner them and then beat them to the point of brain damage (the brothers Munir and Tokeer Hussain). On the subject of man-traps, they have been illegal for about 300 years.
On the subject of how much force you can use, this is worth reading....
(a)that a person acting for a legitimate purpose may not be able to weigh to a nicety the exact measure of any necessary action; and
(b)that evidence of a person's having only done what the person honestly and instinctively thought was necessary for a legitimate purpose constitutes strong evidence that only reasonable action was taken by that person for that purpose.
Section 76(7) of the Criminal Justice and Immigration Act 2008
http://www.legislation.gov.uk/ukpga/2008/4/section/76
What that basically says ....written into parliamentary statute ...is that it's very difficult in the heat of the moment to precisely judge reasonable force, so some latitude should be given ...and that so long as the jury is convinced you were acting instinctively with what you believe to be the right measure of force to deal with the situation, that should be sufficient evidence of reasonable force.
There is a great deal of latitude there in support of the home owner. It doesnt go as far as a castle doctrine, or as far as I would personally like, but it's no where near as bad as the Daily Mail would have us believe. You cant shoot a burglar in the back when they are running away and you cant chase one down the street and beat his brains to mush with a cricket bat, but you can take whatever reasonable measures you feel you need to, in order to defend yourself, your family, your property and other people.
The Crown Prosecution Service legal guidelines on self defence is worth a read...
http://www.cps.gov.uk/legal/s_to_u/self_defence/