To create the company will cost you somewhere in the area of �100, if you find a cheap company to do it.
You'll have to buy a pre-created company (sort of off-the-shelf) then change its name to what you want. It cost me about that sum, but that was 10 years or so ago.
The on-going costs (assuming you're a private, limited company) are the annual return (about �15?) and you will have to do accounts annually, even if not trading. Dormant accounts are trivial though, and you can do them yourself.
No trade means no turnover or profits, so once you've explained it, the tax people don't bother you.