What is the earliest I can sow my chilli seeds without then using grow lights?

[dave_100]

I plan to grow Prairie fire and Ring of fire chillies next year, starting in a heated propagator, then moving to a windowsill. I'm in the south east of England.

I know the heated propagator lets me germinate earlier than with a non heated one, but I'm worried then if it is a cold/ cloudy February for example, so not getting sun, will the chillies then be okay?

Bearing in mind I will be working with natural light only, when should I get germinating?