Welcome to the Workshop community @Ninaninja. It's fantastic to have you join us!
Bunnings certainly does offer a wood cutting service which makes it super easy to do without a saw when starting out. If you take your sizes with you the team there will be more than happy make the cuts. Just be aware there are some limitations on how small the pieces they can cut are, generally no smaller than 30cm across.
It's great to have such a keen new community member with us. Anytime you have a question or want to share a project with the community, just hit the "Start a new discussion" button.