Hi Therese,
You must be very excited about your upcoming trip!
It's great that you know the county your ancestors are from, because the local genealogy centre is probably who you should get in touch with. The records you have may help you find leads.
Mayo has 2 genealogy centres (North and South Mayo), so I hope you know which part of the county your ancestors are from? Here's the contact info for both centres:
https://www.rootsireland.ie/mayo-genealogy/I wish you the best of luck! Hopefully, you can meet some of your relatives while you're visiting County Mayo this May. Even if you won't find them, it must be an amazing feeling to walk in the footsteps of your ancestors. And, there's enough to
see and do in County Mayo.
Please keep us updated about your journey.
Noortje