You Cannot receive a grant for your hybrid heat pump method (such as a combination of fuel boiler and air source heat pump). If you need any aid using your preceding grant, it's best to follow the Ofgem Guidelines to ensure your payments proceed and you satisfy any obligations like https://directoryindexer.com/listings13478739/how-much-you-need-to-expect-you-ll-pay-for-a-good-air-source-heat-pump-installation