I'm thinking of creating a gadget website that introduce visitors with the latest gadgets. The site is also an affiliate marketing site - where I get commision everytime visitors click on the link that take them to the site that actually sell those gadgets, for example, Amazon.
Am I required by law to provide my home address as I have no office address?
Under EU and UK law, there is a (quite widely disregarded) requirement to supply a geographic address in these circumstances.
An affiliate website is very likely an "information society service" in EU law jargon, and so (with reference to the UK implementation of EU law here) Regulation 6 of the Electronic Commerce (EC Directive) Regulations 2002 will apply.
This is not quite the same thing as saying that you have to supply your home address, however it does strictly rule out using a PO Box.