Typical UK flying club practice. If you beg, you are given the "POH". But it is the generic manual, it has been carefully made non-specific.
We always use the weight schedule weight for all of our a/c w/b calcs. It's a military club, no gash practises. Our CFI (ex CFS instructor) is a bit keen on stuff like that.
By the way Ampage, congrats on the XC!