I finally got hold of a copy of the SFX Doctor Who special. Right at the end there's an interview with Elisabeth Sladen, which I have scanned in.
There's also a list of how all of the New Who & spin-offs rated out of 5. Out of 42 of them, School Reunion was 7th and Invasion of the Bane was 13th. Which was higher than any of the Torchwood episodes came. (The top 3 were Steven Moffat's.)