I don't time the chicken. I have the oven on at top temp, put the chicken in and turn the oven down to gas 3 and then leave it for a long time, several hours at least! It's falling off the bone gorgeous. Don't forget to baste it, and you can rub butter under the breast skin.
You will be able to use it for left overs for more than a couple of days as long as you keep them in the fridge and only take out what you want each time. I generally get a roast Sunday lunch, chicken risotto on Monday, chicken sandwiches for most of the week and chicken soup some evening when I can't be bothered to cook.
I take all the meat off the chicken once it has completely cooled, and break the carcass up completely to get at it all (the oysters are the best bit and underneath).
The bones, skin and gristly bits go into a big pan with lots of water, some peppercorns, garlic, onion, carrot (celery if you like, I don't) and gets boiled for a few hours, then strained and you have chicken stock for making chicken risotto, or chicken soup. You can chuck in a stock cube if you think it needs it.