Nigella often uses spices in her cooking. Does she have a preferred source?
Nigella's collection of spices has come from many different sources so we can't recommend one particular brand. However when buying spices try to buy them from a place that has a reasonably fast turnover in herbs and spices, so that they have not been sitting on the shelf for too long. Also unless you use a lot of spices in your cooking we would avoid buying in bulk and aim for smaller jars or packets.
Most spices come with a "best before" date marked on the packaging. Once the spice jar or packet has been opened whole spices will usually last about 2 years and ground spices about 1 year. After this time the flavour starts to fade and you may not notice the flavour of the spices as much in your recipes. Keep the spices stored in airtight containers with the lids tightly shut. Heat and light will affect spices and humidity can make ground spices clump together, so store them in a cool, dry place away from direct bright light. When cooking with spices most will release more flavour and aroma when cooked gently for a few minutes before using, the spices will become more fragrant as the heat up. They can be cooked with oil or toasted in a dry frying pan, depending on the recipe. Saffron and whole dried chillies are usually soaked in warm water (or other warm liquid) before they are used. Saffron "blooms" and releases flavour into the liquid and both the saffron strands and the soaking liquid should be used. For chillies they can be blended with the liquid into a paste to use, or left until soft enough to chop before using. You may like to try Nigella's South Indian Vegetable Curry or Spiced And Fried Haddock With Broccoli Puree.