A month ago, I bought F1. I've now found where I'm positioned in each of the progressions and ran into a "problem".
I am beyond F1 for SLS. The others I'm at least 2 or 3 levels away (still on PE1 for RC actually) so F1 will last me a while for the rest.
I'm a poor student in a poor country so I can't buy F2 yet.
What's the standard approach to this problem?