With a Help to Buy: Equity Loan the Government lends you up to 20% (40% in any London borough) of the cost of your newly built home (upto a maximum price of £600,000), so you'll only need a 5% cash deposit and a 75% mortgage to make up the rest (N.B. You must have at least a 25% mortgage to be eligible for Help to Buy).
Where is the property:
N.B. The above figures are a guideline only and subject to Help to Buy affordability checks and Mortgage affordability checks.