The materials you need for each course are set out in the introduction and preview section, so that you can see what is required before paying for the course. It does vary from course to course. Liz will try and offer alternative colours, but it is the techniques which are important, so do substitute materials. However, it is worth treating yourself to the best materials you can afford. For example, the quality of your paper makes a huge difference. If you don't use watercolour paper, or a poor quality one, you will find it very, very frustrating!