That is, if you use it to run your business, sending it from one department to another for instance, you must, by law, register as a data controller. Registration costs a few pounds, and if you are in any doubt about the necessity to register it's best to do so. There are penalties for failing to register if your use of data falls withing the terms of the data control act, and they can take the form of some pretty hefty fines.
If you simply collect people's names, postal addresses, and email addresses you are unlikely to be required to register, but you must do so if you collect sensitive information, such as religious affiliations, or details of income brackets for instance.
On a general website that has a form requesting personal contact information you must place a hyperlink - as close to the point of data collection as is feasible - saying something like: "Before you provide us with your personal information please read our pirvacy policy"
Link this to a separate privacy page, which should contain the following statement:
"We respect your right to privacy, and will not distribute the information you provide to us, in whole or in part, without your prior consent. Your details will not be passed to, shared with, or sold to a third party under any circumstances, unless we are required to do so by law. We will retain your information securely, and you may at any time (on payment of a nominal fee) request a copy of the information we are holding. You may also ask that the information be amended or deleted at any time. For further information please contact: (provide an email contact address)."
If you do that you'll be doing all that you need to do without actually registering as a data controller. Data controllers must be individuals within organisations by the way - you can't register a corporate identity.