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The answer isn't that much different from a regular business - you hope your customers can finance you.
But if you are looking for funding and you are a social business - and you are in the UK - I'd start with free courses like this one.
It's not accepting applications at the moment but I believe they will have more courses soon.
As the answers to your question will be very location-specific, I'd approach this as a local challenge. Many social business investment funds are funded in part by governments and they probably don't want to fund a company outside of their jurisdiction.