If I sow my seeds in autumn (those who need cold to germinate) I would have to water them evenly over winter. Last year my misting/ watering timer blew up - is there something like a frost resistant tap timer?

I'm not sure if anyone is manufacturing a faucet/tap timer that resists frost, but they make a product called heat tape. it's basically a kind of "tape" that you use to wrap a section of pipe and then plug into a 110v outlet and it stays warm. I've seen some that aren't sticky like real tape. Perhaps you could wrap a timer in heat tape and maybe a little insulation of some sort over that finished with a dry cover.