It is, and always has been, legal to use reasonable force in defence and in prevention of crime.
What isn't legal is (a) excessive force and (b) pre-meditated violence, which includes keeping weapons intended for use as weapons.
Personally, I disagree with the latter. I think it's reasonable to keep weapons at home in case someone breaks in. That doesn't make it legal, though.
I keep lengths of steel pipe easily available in several rooms of my home. I have a perfectly good reason for doing so which does not make them premeditated for use as weapons. You have the same good reason, as does nearly everyone. There are educational campaigns to encourage people to have planned escape routes in case of a fire in their home. In most (if not all) homes, it is possible that a fire may break out in such a way that it prevents you from exiting through a door. For that reason, you should have something handy near every window that you could use to smash the window quickly to escape a fire that way. Hence my steel clubs. I want a way through a window in seconds if, for example, I'm woken up by my fire alarms and my stairs are on fire. Smash the window with the club, drop a blanket/duvet/anything over the base of the frame to protect me from shards of glass and I'm out.
If I find someone has broken into my house and I grab one of these tools and break one of their legs, I think I can claim reasonable force. Who knows what they would have done to me otherwise?