I would actively avoid punting when over 30C is forecast (possibly this coming week??) - simply because i cannot guarantee a cool room (particularly for incalls), and besides hate the extra heat, getting there and back. Might go for a late evening appointment (and this may apply for v warm days, but below 30C), but would more likely just wait a few days - for temperature to be more temperate. The British weather means we wont have long to wait for a drop in temperature from a heat wave!
Ideal would be spring or autumn day(s), I think.