Winter growing

Ok, this mite be a little crazy. I am in the UK and I was wondering if it was a good idea to start growing now outside in my green house. I was thinking if i could prevent my plants from dying in the winter it would effectively just give them a head start for the summer. I would be germinating inside and keeping them indoors for a few weeks.
Is this a good idea?

I'd wait another month or keep them inside until the outside temp exceeds 15C. Your plant will still have a hard night period because of the cold and may even die if not resistant.

Outdoor growers usually plant their seeds in spring so their plants get the full blast of summer in their veg period.