Geoff's correct Sam.
Unless you have/are prepared to heat a greenhouse to keep things going, it's way too early yet for most things. The seedlings are going to get very etiolated with the still lack of light, even if they have warmth.
IME far better to wait until at least mid- Feb at the earliest for most things. Unless it does say on the packet January fine for that particular plant.
Yes, we're all itching to get going, but time spent now checking that you've got all the bits that you need, tidying out shed etc is not wasted & Feb will soon arrive.
J.