Private tenants on Benifits grants for new gas boiler heating and fittings

My private let flat my landlord had a gas line fitted out side for sole use of his property before I moved in. Though inside is an old boiler tank in a cupboard for hot water and electric heating through out the property. All electric, if you are a tenant in a private let, it is possible to get a grant for gas central heating in side, or cavility wall insulation different energy saving solutions. When I was trying for this a company sent me an expendetue form, now it’s not a loan it’s a grant so asking how much I spend on food, travel or clothing etc are unsolicited questions, they don’t really need to no this information, as they don’t need evidence you can afford to pay them back cause its not a loan. Makes me wonder what they do with all the tenants financially information. Now if you do enquire and are sent one of these forms you don’t need to fill it in, or even discuss anything with anyone you don’t want to or know. Don’t feel you have to disclosure your spending.
I was just wondering if anyone else had had experience with a grant. Because before I move I would like to get as much as I can done to improve the quality of living in this property for future tenants and also doing my landlord a favour, it may even add value to his property and make it more attractive for potential tenants. You can also get a grant for double glazing in Scotland im not sure about down south. I am all ears
Thanks

Mark10??? Surely with your vast knowledge of years of renting out property you would no about this after all it’s not just benefiting the tenant but it is doing landlords a huge favour also.