The Parliamentary rugby tournament runs from September 10 to 23 - overlapping with the real Rugby World Cup - and Mr Nash said he believed the parliamentary team's itinerary included attending one RWC event: The opening game at London's Twickenham Stadium on September 18.
New Zealand MPs on the parliamentary tour are personally paying $2500 towards the cost of the trip, with other costs met by corporate sponsors, including Air New Zealand.
"This isn't a serious delegation to solve world peace - it's just a bunch of old guys trying to re-live past glories," 47-year-old Mr Nash said.
"It's not particularly pretty rugby but it's a lot of fun."
Other MPs on the parliamentary team are Labour's Kelvin Davis, Peeni Henare, and Damien O'Connor, and National's Paul Goldsmith, Mark Mitchell, Alfred Ngaro and Peseta Sam Lotu-Iiga.
Seventy-year-old New Zealand First leader Winston Peters is part of the team in a non-playing "media manager" role while parliamentary staff and family members are also involved.
"There are a number of countries that are represented and it's a fantastic opportunity to meet parliamentarians from other countries over a beer after a rugby game," Mr Nash said.