Halsall is a medal hope for Britain at the 2012 London Olympics

Halsall, from Liverpool and Lincoln star Simmonds, both 16, made their international debuts last year.

Both are looking to gain experience before focusing on next year's Beijing Olympics and then the London Games.

"My ambitions are to have a good time and get experience. There is not really any pressure," admitted Simmonds.

Freestyler Halsall competed at the Commonwealth Games in Melbourne, finishing fourth, before steering the 4x100m medley relay team to victory at the European Championships in Budapest in a new British record.

The City of Liverpool swimmer will compete in the 50m, 100m and 4x100m relay and admits she has matured over the past 12 months.

"This time last year it was my first big senior competition. I was going from junior to senior. Now I've got more experience and know how to deal with things," she said.

"I'm stronger. I've got more belief in myself and in my swimming.

"Everyone is a lot bigger, it is more professional, more serious, it is a step up in every way you can imagine."

Simmonds, the youngest member of the British team, was fifth in the 200m backstroke at the Europeans before winning bronze at the European Short-Course Championships.

The Lincoln Vulcans swimmer has already competed down under when she swept the board at the Australian age group championships in 2004 and she believes the British team can prosper.

"The crowd can make a lot of noise. I think we are underdogs but I think it can put pressure on the Australians," she said.

"They are favourites but it doesn't mean we are or can be any less of a sporting nation than them."