Are you using fresh pumpkings? If so, just google for a recipe that will tell you what to do.
In the USA they sell canned pumpkin and that's what I use. The recipe is printed on the can but I always add more spice as my family likes that.
They make sell pumpkin pie filling (it's already got the sugar and spices and other items in it and is ready to be put into the crust for baking).
You do cook it in a raw pie crust BTW.
You add eggs, pumpkin pie spice, condensed milk, sugar, possibly butter....
Why don't they sell it there? My stepson lives in New Zealand and they don'd sell cornmeal, just corn flour. I'm a southerner, originally from Texas, and you just have to have cornmeal to cook with. You can't make good dressing without it and fish fried in it rather than corn flour is absolutely heaven. Can you buy cornmeal in England?