Unless there are exceptional circumstances, under the terms of your shared ownership lease you are not allowed to let your home if you only own a part of it (although you are usually allowed to have a lodger who lives with you). To be able to staircase to 100%, you’ll need to pay to get a valuation done by an independent Rics-qualified valuer. Then you need to calculate whether the money you inherited will be enough to cover 75% of the valuation or whether you’ll need to increase your current mortgage to be able to buy your home outright. If you switch to a buy-to-let mortgage you’ll have to pay an early repayment charge because you’d be paying off your current residential mortgage before the five-year fixed-rate term is up.