There are a wide range of grants and funding options out there not so sure about the "not having to pay it back" though others here may know more. Have a look here at the AXA link they have a lot of detail on the topic and quite a few links to help you find the right source:
The type of grants you refer to, are usually grants are based on you helping the local council or government fill some targets that are usually meaningless and a waste of time overall, but are there to fit targets they need to hit.
For example, you may get £5,000 to make the roof of your office building 'eco friendly' by putting soil up there and grass seeds - However, you have to match the grant. You put in 5k and the council puts in the other 5k.
Technically you've had a 5k for "free" but to what benefit to you? Not much really. You've spent 5k to have grass on your roof. The council can boast they're an eco-friendly council and support businesses.
It's mainly things like that. Or you spend £10k to help promote tourism in your area and they'll give you £5,000 as a grant for doing so.
Grants are virtually always about you fulfilling targets the council need to hit, so you are helping them, rather than them giving you grants, to help you. If that makes sense.