There appears to be an unusually large epidemic of ignorance in blogland concerning English law, particularly with respect to burglary and freedom of speech. But don’t worry, SBBS will enlighten you.
Most importantly of all, unless you are qualified to practice law in the UK , you should not try and derive what you can and cannot do based on your interpretation of what the words in a given piece of legislation mean. This is not relevant.
Case law is, however, relevant. For existing laws, this means "who has and has not been convicted under this law, and what sentence the ones who were convicted have received". The burglary example is easy, then: you have the right to kill a burglar in your house unless the prosecution can prove beyond reasonable doubt that you were not acting in self defence. This is not possible unless you shoot the burglar as he runs away, stab him 12 times in the back, or do something equally vicious, murderous and depraved. The only people to be convicted are people who fail to follow these guidelines (pleading guilty to a crime that you are not guilty of is unwise and unfortunate, but again easily avoided).
Case law is also frequently important for new legislation. David Blunkett’s daft religious hatred law is an example: it (literally) takes the existing racial hatred law and adds ‘or religious hatred’ to it . This makes racial hatred caselaw directly relevant.
You have to try very, very hard indeed to be convicted of incitement to racial hatred. Delivering a speech or handing out leaflets that say "How do you fight a Jew? You kill a Jew" or "The Jewish people must die" will do it (Jews and Sikhs are considered races in the context of this law). Distributing the blood libel  also cuts it, presumably because of its history, as does malicious Holocaust denial ("I don’t think the Holocaust really happened" is a legal thing to say; "The Jewish scum made up the Holocaust so they could claim eternal victimhood and continue to rule the world" is not). Trying to stir up a local race war also does the trick. That’s about it.
So according to precedent, making a speech that says "send the blacks home", writing a book that claims black people are stupid, defaming Guru Nanak, or even performing a black-and-white minstrel show in which Guru Nanak denies the Holocaust will not earn you a conviction – unless it can be shown beyond reasonable doubt that you’re doing so in order to stir up a race war.
I don’t like the principle that the new law would bar me from standing in Brick Lane shouting "Islam is bloody stupid! Go study some science!". But a post on a weblog saying "Islam is bloody stupid; people who currently follow it should go study some science" will not be criminalised. And it’s important that people are aware of this, since it would be a shame if they avoided perfectly legal criticisms of religion through fear of prosecution.
Indeed, most of the blame for the misunderstandings surrounding this law falls on the government: they seem to be trying to convince Muslim lobby groups that the law will ban many more things than it actually will. Presumably they figure that by the time the Muslims notice that it doesn’t, the election will already have happened. And George Galloway will have won Bethnal Green & Bow anyway…
 I am not. If I were, I wouldn’t post anything that could be construed as legal advice on a weblog, as I could be held professionally liable for any advice I gave.
 Religious hatred is defined as hatred towards "a group of persons defined by religious belief or lack of religious belief". And yes, I know this involves my interpretation of what the words in a law mean; in this particular context this is permissible, since the way the law defines ‘religious’ is not at issue.
 The claim that Jews drink Christian babies’ blood. This is not only a nasty meme, but a very strange one, given that observant Jews aren’t allowed to drink anything’s blood.