If i want to apply for a job, should i state that it's seasonal?

I’m wanting to apply at the hospital to be a kitchen helper. I’m only wanting to work it for the summer though. Although i’m not too sure if i want to state that i want it to be seasonal, since if i like it, i may want to continue working there.

On my cover letter i started off with “I am interested in a summer position at….” what would i need to put if i’m not sure of it being seasonal or not?

Also, in August i have many plans and may not be able to work as much. 2 weeks off in toronto with my family, and a day off to go to my aunt’s wedding ceremony. If i get contacted, will i need to tell them my plans at my interview or will they not hire me if i told them that?

Please comment. :P