My characters are an irish businessman/father at 50 years, a 28 year old male, unemployed/ drinks frequently (part Irish/Aussie), two 16 year olds male + female (male is Australian) (female is part Irish/Aussie). A 201 year old female, unemployed/australian. Two 3 year old twins, male/female- both Australian.

my characters are ... A 201 year old female, unemployed/australian ...
I love the thought of a 201 y/o character in this book! Wow! The story arcs that can develop from that have amazing possibilities!

Check out the most popular names for babies in the years your characters were born, and pick one that sounds right. You can also get lists of the most common surnames for different countries or ethnic groups.

For your 50 year old Irishman, you might have a name like James, Michael, Robert, John, David, William etc. If he's from around Dublin, Byrne is a common surname, or Reilly or Daly if he's from the midlands.

OK, but I need a name for her

Thanks. I might use Robert Daly, sounds OK?

Bindi.

Robert Daly sounds good, Irish but not stage Irish. I'm so sick of Paddy Murphy.