If so seal the joint in a frying pan with some onions. Then put it in the slow cooker, pour some stock into the frying pan with a big glass of red wine and stir. When the stock is hot pour it into the slow cooker. Add bay leaves and a bit of black pepper. Leave it on high until it is simmering slightly round the edges and then turn to low. Keep cooking it for a good 6hrs or so.
OrmIrian's recipe is good. You can also do it in the oven if you don't have a slow cooker. Do just as she says, but put it all in a casserole. Cover with tinfoil, then put the lid on the casserole. Cook at mediumish heat until liquid is bubbling, then turn down to very low and cook for about 3h.
I then take the meat out, pour everything else into a saucepan, and put the meat back in the casserole. Cover the casserole and put a newspaper and a towel over to keep it warm while making the gravy. Fish out the bayleaf, liquidise the stock and onions, add a tablespoonful of flour and simmer, stirring well, until thickened.
meg - brisket can be quite tough and it isn't usually recommended for roasting. That is why it's a cheaper cut. You can braise in the oven but you need liquid with it so you need a dish with some sort of sides rather than a flatter roasting tin. Ideally cover it too.
Could you cut it in half and use on of your smaller casserole dishes.
This is not the one I usually make (I do the one from Complete Cookery Course) but it looks pretty good. I'd throw in a few veggies with the meat - shallots, 1/2 celery stalks, baby carrots and let them braise at the same time. The red onion marmalade would be optional, but nice, I think.