I would see an accountant ASAP and get a few tips, this is not really the place for the level of expertise limited companies need. You never know he might put to you that it is not worth the trouble. There are some benefits to being a sole trader, and some to being a limited company.
example.
One of the things you should ask him about is "goodwill". If I remember correctly you can sell your window cleaning round to your limited company. Goodwill is not normally tax deductable, however, I believe that when transfering goodwill from a non-limited company to a limited company it is (ie the limited company gives you the correct market amount for the goodwill).
Like I said, ask your accountant as it is way too deep for assumptions like the one I just made, and any others you read about saving ect to be relied upon.
Personally, if I was less than 50k (which obviously I am no where near), then I would not bother. Frankly you could earn more (assumption) canvassing good work than you would save spending the same time doing paper work. But ask your accountant as he knows more about you and the subject than anyone on here.