How can I defend myself ?

Politicians make brave announcements telling the public that they are free to defend themselves in their own home4s provided that they don't use disproportionate force.
However, when I read news reports like this, the immediate question is "How?". Here a 73 year old man was stabbed to death in  the early hours by a burglar whilst trying to defend his wife.

What can us oldies do to defend ourselves?

Even under the "relaxed" policy, it still appears that it is illegal to keep a suitable weapon in your bedroom as that would be considered to be premeditation!
Ideally, I would like a handgun, but this is clearly never going to be allowed in this country, in spite of statistics showing that the burglary rate in the US is lower than here simply because burglars are not prepared to take the risk that the householder has a gun and knows how to use it.
The next best would seem to be a spray, as issued to the police for self-defence but again these appear to be illegal, although, like guns, the criminals have no hesitation in having and using them. I could, it seems, buy one over the internet, but as I'm only prepared to use my credit card for reputable traders, this seems to be ruled out, regardless of the legality. They are available, legally, in some European countries, I would have thought under the EU that you should be able to bring into the UK any item purchased legally within the EU, but somehow I doubt it - rules only work against the citizen, not in his favour.
I can't even do what a friend of mine (RN Ret'd) does. He has his Dress Sword hanging in the wardrobe with his uniform, and as he says, it's suitable for more than ceremonial occasions.
My present thoughts are towards sprays such as aerosols or perhaps a small fire extinguisher. Which has the best range and is most likely to blind or otherwise damage an intruder? The fire extinguisher seems the best option as it could legitimately be in the bedroom ready to hand.
Any other, reasonably legal, ideas would be welcome.