Can I sow leek seeds now .. Do they need heat to germinate

It's still a bit early for leeks tbh and they don't need heat to germinate, anyway.

DD's leek advice is here, it's an old thread - but the method still works every year for me - so why change it
https://chat.allotment-garden.org/index.php?topic=26363.0

I would say it is much too early to be thinking of sowing leeks.
Mid march would in my view be the earliest for even thinking about sowing them.

I sow my Leeks in April in an unheated greenhouse in deep trays. They germinate in about 12-14 days.
At the end of May or first week of June I plant them out when they are about 6 to 8 inch tall.

My father keeps telling me my grandfather used to sow leeks in January, so yes you could sow now, and no, they don't need a propagator. He sowed for show, which may be the reason for the early start.

I have sown leeks in early February before, and they did grow fine, up until they bolted in late summer. I normally sow in March, and that has always worked fine for me.

The problem with sowing very early is you can end up with a load of seedlings outgrowing their trays/pots that you can't plant out because it is still too cold or the ground isn't ready.