Nicky
One of our favorite weekend activities right now is building rockets with the children and launching them with our friends. We love to build and customize our own, but you can buy ready-made ones as well. Its so much fun to see them go up in the sky and then the kids get to run after to catch them.
If you want to try it out with your family, this site has a lot of options for different skill levels, and offers live support if you have any questions as to which rocket would be best for you.
http://www.amainhobbies.com/index.php/cPath/1683_1684/n/Model-Rockets-Kits/page/1