Don't know about "from scratch" But I always make a gravy from the pan while the roast meat is resting.

Put pan directly over heat (on Low), add a decent dash of water/stock or wine (red for red meats and white for Chicken). Use a spoon to deglaze the pan, lifting all of those gorgeous baked on goodies!

Throw in a spoon of flour (plain) and stir (or wisk if necessary) your gravy to make sure you don't have any lumps. You then need to cook this off for a bit, the flour will thicken up the gravy but you need to cook it so that you don't taste the raw flour.

Add more water/stock as you need it to make the gravy as thick/thin as you want.

Then add in any other flavourings you may need, salt and pepper, my favourite is a tsp of vegimite for a real kick - great in beef, lamb and chicken gravys.

And you are done!!

You could always follow Paul Kelly's advice and "don't forget a dollop of tomato sauce for sweetness and that extra tang"!!