I'm currently an undergraduate, and I know for sure that I am going to do a MA before a PhD. I am also tempted by the year abroad scheme at my university. I know it would be a great experience, but is it a waste of a year as I know I want to end up in academia, and could do research abroad in the future, and will be spending many more years in the education system?

I'd say do it. You never know if you are going to get another opportunity. Although you say you want to do an MA and PhD, life sometimes gets in the way and things occur that mean this may not happen. It may not be much else, but it definitely won't be a waste of year. It sounds cliched but you will be surprised by the things you learn about the world and about yourself by immersing yourself in a different culture. Also, why jump into a career straight away if you don't have to?! Take time to enjoy life before reality sets in :)