how to get a housing benefit?

You don't. Housing benefit is to pay for your rent or mortgage payments if you are on a low income. You are not paying that, your parents are, so it is up to them to apply for it on the basis of the total household income being low. ESA and PIP are there to cover your other living costs.

Yes, those benefits don't cover housing. But Mum and Dad don't need any extra money for housing because it would still cost them the same to live there even if you moved out. So you can't have housing benefit. That's the way the thinking goes.

You would only be eligible for housing benefit if you had your own place to live in and had to pay your own rent. If you did, then you would apply to your local district or borough council for it.

You would also apply to them for council tax reduction. You can't get that either where you are now because of how council tax works - live on your own like me and you get 25% off, the full amount is for two adults, any extra adults don't result in more tax. So with Mum and Dad there, they pay the full amount and you don't cost any extra.

Edit- isn't it amazing that people thumbs down a totally correct answer.

That is what we pay Social Workers for, Advice .

I worked at a Hotel, the manager hired seven new maids.

Two weeks later they all quit. Their Social Worker told them they would make more money on the Welfare than actually working for a living.