It's probably a relatively good sign if they are asking for more information. I imagine your university has some guidance for degree standards somewhere online? Typically UK and Irish universities divide degrees into first and second class honors (so called 1:1 and 2:1). There are lower degree classifications but you won't get into grad school unless your grades fall into one of those two categories.
The requirements for a first class honors degree involve grades that are, as a weighted average based on credit hours per course, above 70. Your university should spell out its system somewhere online or something should be available from the registrar's office to help you.