OP, are you in receipt of the Severe Disablement Premium? If so, you'll be in the support group of ESA.
I think your comments regarding your LL and their income are irrelevant and not yours or a forum's business.
When you applied for the tenancy, you would have had to provide evidence of your income. Surely that would have been made up of ESA and PIP if you are in receipt of PIP.
I'm struggling to grasp why you're now applying for housing benefit. Have you sought some support from CA to manage your welfare rights?
Because you've had a change in circumstances, that may well trigger you to apply for UC. Transitional protection is now in place for disabled claimants. As far as I can see, a new claim for housing benefit is only for people on SDP. If you are, then those entitlements would surely have formed part of your income?
You really do need to have a conversation with your LL and set down your position as they will be worried going forward. Under housing benefit, you will have been asked if you struggle with budgeting whether your like your HB award to be paid directly to the LL.
Any LL.cannot accept 'my friend' was going to help me out. Can you accept this?