My granddad sold his house for an operation by one of his

Who owned the property, and who’s will are you talking about?

Do you have a copy of the will?

Your grand dads will only takes affect when he dies.

It is not possible to say where you stand without seeing both wills.

Also who the grandparents owned the property when both alive. Joint tenants or tenants in common. That makes a major difference and can actually invalidate parts of a will.

OK, then if the house was owned by them as joint tenant, the property automatically passes to the other surviving owner automatically outside of any will. It is called the law of survivorship.

Any clause in any will leaving the property to someone else would fail, and that clause in the will would not count.

So as joint owners, when you grandmother died, the house automatically became the grandfathers. Any legacy regarding the property in the grandmothers will would fail and not apply.

So as outright owner, your grandfather can do as he wishes with the property and does not have to give anyone anything.

What is sited in his will only takes affect on his death. If the property os sold and does not belong to him when he does then any legacy in his will relating to that property also fails, no one can inherit what no longer exists.