Let me just grab the gov.uk page on knife carry.
Selling, buying and carrying knives
As far as i know English law everything needs to be reasonable force. And that of course is decided by the courts so you have to articulate your reasoning and justification for it.
And there is a terminology difference between weapons (deadly weapons) and objects pressed into service as weapons (dangerous weapons), not entirely sure where to find that for English law though. I could just be conflating some U.S terminology i saw.
As far as i know there is no issue in using a object to defend yourself so long as you can justify the force as long as you dont carry one strictly for self defence anyway. For example if you picked up a brick on a wall and used it, or used your walking stick.
But then the point somone made was, weigh up the legal punishment with the loss of life/limb and decide for yourself if you wish to follow it or not. If your going to get a slap on the wrist then maybe you should just disregard carrying law. Or if you are going to get life in prison, you are damned if you do damned if you dont.
Oh and if we are posting memes: (language warning)