If you think you're likely to get into printing, yes, and honestly, the £20 is a tiny cost relative to the overall cost of shooting and darkroom printing film. Once you've got familiar with the process and tuned into what they do, there's a fair jump in contrast between the grades, especially as you get into the 3-5 region. The slight caveat is if you were only split printing, when you'll probably find you only really use 0, 1 & 5.