I wrote this on here ages ago - should be fairly foolproof:
Roast Chicken.
Remove all packaging, and clean out all the guts from inside. Open up the legs, and place a half lemon inside (whoo-hoo etc). Place the chicken in a roasting tin.
Smear the chicken with butter. Slice a couple of small cloves of garlic, and place a slice in between each wing and leg. Drizzle the whole chicken in olive oil. Add 150ml of water to the roasting tin. Liberally season - i.e. add lots of salt and pepper.
Cooking method. Place the prepared chicken in a preheated oven at 190c. The secret to getting that moist chicken is to baste the chicken at least every 20 mins. It will take somewhere over 1 hr 15 depending on the size of the chicken The way to tell that it is done is that when you tip it, the juices will run clear.
Tip the juice from the chicken in the roasting pan and then remove the chicken, place it on a chopping board and cover it completely with tin foil. Allow it to sit for 10-15 mins. It will not go cold, and all the juices will soak back in.
Gravy
Boil a kettle, and add a relevant quantity of boiled water to the roasting tin. Pour the contents of the roasting tin into a separator jug, and leave to settle. Pour the separated gravy into a saucepan, and place on the boil. Do this whilst the chicken is sitting, and whilst vegetables are on. Bring the gravy to the boil, and then drop to a simmer. Take a mug, and add a teaspoon of cornflour, and enough cold water to take the mug to about 1/8th full. Stir thoroughly, and then add some of the boiling gravy to this mug. Stir thoroughly, and pour back into the boiling saucepan. This will thicken the gravy slightly. Add a splash of red wine. Switch off. Don't worry about the skin that may form. It's only fat based.
Don't throw away the fat in the separator jug - put in a mug, place in the fridge for next weeks roasts....
Roast pots.
Maris Piper or King Edwards. Peel and cut into the correct size. Place them into a pan with cold water covering them and a liberal helping of salt. The salt is important as it keeps the composition.
You can do this as soon as the chicken goes in, as it takes the pressure off. As described above, boil to the point that you place a knife into one, and it gently slides off the knife. Drain the potatoes and leave them to sit for a while. Leaving them to go cold is a form of blanching, and will ensure they have that fluffy centre.
Work the timing backwards. They will take about 45 mins, so estimate when you'll have to put them in the oven. It doesn't matter if you're early as when the chicken is removed, you can leave them in the oven and they will stay hot.
About 5 mins before the pots are due to go in, place a roasting dish for the pots in the oven with a large lump of goose fat in (available from any supermarket). Give it 5 mins till the goose fat is melted and spitting, then remove the dish, add the potatoes. Season throughly (lots of salt and pepper). Place in the oven with the chicken (about 45 mins into the chicken's cooking time depending on size). You'll want to turn them at least once during their cooking time. Keep an eye on them, and you'll see when they're ready. They'll have that golden crispy look and will taste amazing.
That lot should help. Remember if you make yorkshires that you shouldn't really open the oven, or they may not rise properly. Don't buy ready made. It's flour, milk and a little butter for god's sake! Veggies. Don't overcook them. The best way to see when they're done is to taste them. Cook carrots in butter and sugar. Caramelises to give a sweet flavour.