I have read her books, and they seemed to be well researched.
Maybe I need to be more critical of their contents.
I have read quotations from the police in Britain, where they advised people to not fight back against attackers, and not to interfere if they witnessed an attack. Of course, simple advise is not legally binding.
Even on the street in several American states, the legal requirement has been that you are required to retreat if possible, to avoid a confrontation.
This is only recently being reversed, by adoption of what is called here the "castle doctrine" law.
Is it possible that the laws on this vary from England to Scotland, to Wales?
WRT weapons, in addition to guns and knives, you are, unfortunately, not allowed to carry any object in public for the specific purpose for using it as a weapon. This isn't to say you can't carry something that can't be used as a weapon, but you would have to justify having it on you for another reason (I carry an unbreakable umbrella for example (google it). I can justify this, because it is an actual umbrella, it just happens to be a very robust one that won't break if I had to use it on an assailant's head.
However, walking around with a baseball bat would be difficult to justify.
In the home, there are restrictions on owning firearms or explosives, but you can own anything sharp or heavy, or buy a crossbow, and use them if need be, although because of the grey area regarding what is 'reasonable force' you might end up having to try and convince a jury that you aren't a violent nutcase for having a collection of exotic weaponry spread all over the house...
No, the laws on self defence are the same throughout Britain.
Other laws may vary, but not this one. There are three legal systems in the UK: Scotland, England/Wales, NI.