In Ireland - well at least in the North - bedding plants and veg for planting out are behind because of what is jokingly called the spring in those parts. This can be a major advantage of a green house.
Now if you want to make a bit of pocket money you can grow these for yourself and sell the inevitable surplus. This also has the advantge of clearing out the space for the summer crops e.g. tomaotoes, cucumbers etc.
By the way you do need a gap in the growing schedule to sterilise the soil and the total green house. Because of the humid conditions in Ireland, it is essential once a year to make sure you are totally clear and 100% sterilised. You may get away with it the first year but subsequent years it is essential.