I'm intrigued that NASUWT seem to think that teachers can refuse to cover for absence. The STPCD 2011 says "..teachers may cover only rarely, in circumstances which are not foreseeable", meaning they're contractually bound to cover (albeit rarely) for unforeseeable absence. Fair enough, we may see unions interpreting 'foreseeable' more tightly, but the notion that anyone can refuse to cover isn't strictly accurate. As we (Supply Teachers) are employed to wholly or mainly provide cover, I assume we're still working 'to rule' if we cover because that's our job. I still don't plan to be available for work on 30 Nov though.