Living in the desert, summer tap water is 30°C or more, and then not much above 30°F in the winter, so I'm perhaps a bit more careful than I would be in the UK...
So winter, I use kettle water to bring my mix water up to about 20°C, and in the summer I just the water or the fridge, and kettle again to warm it up!
My stop and fix are stored at room temp, which is consistently 70-80°F.
Colour is a different matter - for that everything goes in to the water bath with a sous vide immersion wand, then when the film is developing, everything except the tank comes out of the water bath do the rest of the chemicals / final wash can drop to their trips before use. Washes before the last contre out of the pre-heated and measured tap (80-100°F recommended, so I measure at 90 then don't move the faucet's handle!)