Every company should list its company registration number, place of registration and registered office address on its website. That's the law in the UK if you're a limited company.
In 1985 it became a requirement to include these details on your communications such as letters, invoices, orders and so on. Then of course there wasn't an internet as such.
Since 2007 it has been a requirement to include these details in your email footer, websites and any other electronic communication. There's a lot more information on this on the 'Outlaw website'.
What else do you need? Apart from the above there aren't any other statutorily required items though we do recommend that you have a terms & conditions page that sets out legally how your company does business. Your website is the perfect opportunity to do this. You don't have to have it in the main navigation but it should be reasonably easy to access. You should also link to that page in your emails. In the future, should there be any dispute, you will be able to point to the website page and the links to it. I would also suggest getting it professionally written for your business. Every business is different as are their liabilities, so getting a template T&Cs off the web is a bad idea. You'll discover that when you then come to rely on it to sort out a problem. I can recommend Michael Milne of Ilisi a barrister who has a great deal of experience in these things . It really is worth getting this part right.
The rest, well that is down to you.