With equity release, the amount of inheritance available will be the difference between the proceeds from the sale of the house and the amount outstanding on the plan when it's redeemed.
We can't predict the future value of your property when it's eventually sold so we can't predict what inheritance will be available.
Some providers offer an inheritance protection facility on their plans which lets you protect a specific percentage of the property's future value. Your advisor will discuss this option if one of your priorities is protecting an inheritance.