U.S Visas and entry:

Currently, many British citizens travelling on a valid, individual machine readable passport, with a return or onward ticket, and who are staying for less than 90 days, qualify for the Visa Waiver Program. There are conditions, so you will need to clarify.
www.usembassy.org.uk

(they do not have a .mobi address yet so you may have trouble viewing from mobile)

Operator assisted visa information callers from within the United Kingdom should dial 09042-450-100.


Austalian Visas and entry:

This is a superb site with a wealth of knowledge.
Again we can't guarantee a perfect browsing experience from a mobile device as they don't have a .mobi website.
Here is link for a wealth of information:

www.citizenship.gov.au/
This is not a .mobi site so we cannot guarantee it can be viewed from a mobile device.