In answer to Countrymummy’s request, and in the presence of Seville oranges, I have information about marmalade!
I’ve been making it for years, and, despite owning a handwritten copy of my grandmother’s recipe, I have had the most reliable success from an unconventional Delia recipe which you can find at Delia Online here. It takes longer in time, but not in effort. Juicing all the oranges and cutting up peel is much less hassle if you poach the oranges first, a la Delia: you can scoop out the oranges' innards with a spoon (all that pith comes away), and it is easy to slice up the skins to the thickness you like. Don’t do it in a processor, the bits end up too small. It is worth making, honest!