Congrats on deciding to do a tri!

You can probably already do the bike and run but you'll want to practice them at least twice a week.

It sounds like the swimming is going to be you problem. Breast stroke is easy to do but I find that it really tires out my legs and makes my knees hurt. If freestyle isn't an option then I'd suggest going with side stroke. It's my go-to stroke if I get overwhelmed.

Remember to try to have fun.