Help to Buy: Equity Loan is a government scheme to help first-time buyers get a property. You need a minimum deposit of 5% of the purchase price and a repayment mortgage of at least 25% of the purchase price. You can then borrow an equity loan to cover from 5% to 20% of the purchase price of your newly built home. If the property is in London, you can borrow up to 40%. 

The equity loan percentage you borrow is used to calculate your interest and equity loan repayments.
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You can no longer apply for a Help to Buy equity loan. If you applied before 6pm on 31st October 2022, your application will still be processed, but you must complete (i.e. legally own and occupy) by Friday 31st March 2023.