Don’t throw it away!! I have a real aversion to wasting perfectly good food, especially nowadays. I agree to disliking cold lamb, but there are plenty of ways of using it, as many grans have already posted.
If enough of it is actually sliceable, I make some gravy and lay the slices in. Make sure the meat is covered with gravy - I use a frying pan. Bring to the boil for a short time then simmer until the meat is piping hot. All you need then are some potatoes and veggies for a lovely dinner! And if you don’t want to eat it in the next few days, freeze the slices and use in the same way whenever you like. In fact I’ve got som frozen slices in the freezer now and it’s given me an idea for tea ….