How I'd make gravy -
Take the bird out the pan. Pour off the juices into a bowl. The fat will seperate out on to the top. You can skim most of this off.
Assuming you've cooked in a pan that can take direct heat from a hob, deglaze (i.e. heat and scrape about) all the burnt and sticky stuff with a little wine. If you have a potato masher, mash down any veggies, bits of garlic, etc in the pan to get all the juices (& flavour) out of them. Put the resulting mush in a sieve, pressing it down to squash every last bit of juice out.
Add the liquid below the sieve and the cooking juices from the bird (and any carving juices) to a saucepan and heat. Boil away or add water to get the desired concentration of flavour. Add cornflour to thicken if you like. Prefer this sort of natural gravy to Bisto, but others will probably disagree!