To travel to Australia from the UK you will need a full UK passport. Your passport must be valid until at least 24 hours beyond your return flight to the UK (but preferably longer, in case of any unforeseen delays at departure). Holders of any non-British passport should check with their relevant embassy before departing.
British citizens need a visa to travel to Australia. British citizens can obtain an eVisitor visa direct from the Department of Immigration & Citizenship. There is no visa application charge or service fee for this - visit http://www.immi.gov.au/visitors/tourist/evisitor
A eVisitor visa will allow you to stay in Australia for up to three months on each visit within a 12 month period from the date of grant.
You can find out more information about Australia entry requirements at the Government Services and Information website
No sharp objects, including pen knives or nail clippers, scissors or files, must be taken into the plane cabin. All liquids may also be refused in cabin baggage, unless you can prove, with appropriate certification, that they are for essential use (please check your airline’s documentation for its specific policy on this). Such items will be confiscated unless they are in hold baggage.