On the subject of the authentic ruby, the most important ingredient is the foil box with cardboard lid.
No great mystery here but you make a "curry gravy". Loads of recipes on the internet but its just some onions fried but not till brown with some garlic and ginger. You a little tomato and...
You can. Just buy a whole free range chicken. For say 7-8 quid.
Learn to joint it your self and you will get a number of meals out of it.
From the leg and breast meat, 2-3 curries which you can freeze.
From the thighs some blinding Spanish rice.
From the bits you can't eat, make soup.
A...