"full atc now fire service cat five can go up to 6 or 7"
From what I understand it's still fire cat 4 Mon-Fri and fire cat 2 on weekends, though availability on request to fire cat 6,
Seeing as they've struggled to get fire cat 4 in the week at times, and rarely can get fire cat up to 3 or 4 at weekends even with notice think that getting fire cat 6 up for any diversions would be pretty much impossible.
Fire cat off the notams now, but a permanent addition to the AIP, less likely to be asked hard questions about fire category if not on the notams I suppose.