Seeds...

Several flowering plants can be grown from seed now, such as Aquilegia, Gaillardia, Hollyhocks, Nepeta, meadow poppies, violas, verbascum, Rudbeckia, sweet peas and Laurentia, All Year Round cauliflowers can also be sown.
There ae probably others, these are the ones I intend to try.

Don't be tempted to start off too many seeds yet as you'll be stuck for space in the greenhouse before they are ready to go out. However, you could try small amounts of seeds that are recomended for early sowings. Often, later sown seeds just catch up and there is no advantage, except to satisfy your urges!! Hardy annuals would be best to try.

I was too impatient last year and by the end of February I had a lot of seedlings and not enough room. As Volunteer said later sown seeds (particularly annuals) do catch up.

The perennial Penstemon is a good one to grow from seed now as a January sowing ensures it flowers this year.
In fact many perennials will flower in the first year if sown in the next few weeks, so why not try a few of them and leave the annuals until next month..