I would like to make the LIGHT GLACE FRUIT CAKE from my well-thumbed "Delia Smith's Christmas" for my son's 50th birthday in June. I shall have to double the quantity to serve the number of guests. I have a tin which measures 12" x 9" x 2" (sorry, I've never learnt to cook in metric!). I would be grateful if you could please tell me whether the double quantity would fit in the tin, and what the cooking temperature would be. Many thanks - I really would appreciate your help.