I think this man should hopefully be okay in regards to being charged with murder according to this.
Using reasonable force against intruders
You can use reasonable force to protect yourself or others if a crime is taking place inside your home.
This means you can:
protect yourself ‘in the heat of the moment’ - this includes using an object as a weapon,
stop an intruder running off - eg tackle them to the ground.
https://www.gov.uk/reasonable-force-against-intruders