Although some registars don't care about whether the personal information is real or not,I think you should give them the real information.If you really don't want others to see your information,you can ask for privacy registration.You'd better contact their representatives to modify your address so that they can give you better service if they want to notify you something from your address or other situations.Well,that's just my advice.
What should be your purpose to provide them a fake address information. You can have privacy protected information on your domain if you wish. But why fake address?
I thought I'm an Indian so it would be a problem with co.uk domain and I don't want to show my details on whois thats why I given one uk fake address.not for any illegal purpose.
If someone makes a complaint then you could run into problems, fly "under the radar" and you should be fine. why use a fake address though, just pay for whois guard.