A couple notes:
If you were an attending or supporting member of the 2019 Worldcon in Dublin, then you are already eligible to nominate for the 2020 Hugos. But you will need a 2020 Worldcon membership in order to vote on the finalists.
The Hugo Voters packet is entirely dependent on the generosity of the finalists (and their publishers). Some provide the entire work, others provide a sample, and some choose not to participate at all. To give you an idea, here's a breakdown of what was provided in the 2019 packet: