I live in the United States and find that some of the ingredients called for in Nigella's books are not easily available here, i.e. Almond flour. Do you have a list of places that would stock uncommon ingredients?
We are sorry that you are having trouble finding almond flour which is made from finely ground almonds. For the US versions of Nigella's books we do make every effort to try and offer the appropriate substitutions wherever possible. Almond flour is often sold labelled as almond meal in the US so you may find it under this name.
You are most likely to find almond flour/meal in cake decorating stores and natural food stores (often with the gluten free flours). It is also sold in many branches of Whole Foods. You can also buy almond flour/meal on-line from Bob's Red Mill and New York Cake and Decorating (see links below). In the UK almond meal tends to be made from blanched or skinned almonds. We have noticed in the US that sometimes the almond meal is made from unskinned almonds (especially in natural foods stores) so has some brown flecks in it but have not noticed any real difference in the two in baking. However if you are making marzipan or a cake with a very white finish then you will need to buy the version made from blanched almonds (both the suppliers listed below sell the blanched almond variety).
Also in the US you tend to have to buy almond flour in relatively large packages so may have more than you need. As almond flour can turn rancid easily, particularly in warm weather, we suggest that any surplus is stored in the refrigerator or freezer.