Roast the chicken (mine was a cook in the bag - 1hr 25mins at 190 degrees). When it's cooked, I strip the meat from the bone and put in a large flat pan with the gravy. (bisto is the easy option)

Heat the oil in a roasting pan in the oven at about 200 degrees and then add the potatoes.. New potatoes this time.. Takes about 40-50mins

Carrots, Cauliflower (boiled) and leeks (steamed) take about 15-20 mins.

For the white sauce... Half an ounce of butter and the same of flour and half a pint of milk. Melt the butter and then mix in the flour to make a roux paste. Gradually add the milk, stirring all the time (I use a spoon to start, then a small balloon whisk), when it's all in, beat with the whisk to avoid lumps and stir until it thickens