Datasets to practice on while studying data science- and would spreadsheets be considered a stepping stone?

Hi,
So where would one find a dataset or three while self-studying data science to practice on? And if there are any, would their size be an obstacle for the consumer-level laptops and desktops that are typicaly used today?
I am looking for datasets to populate Google or Calc Spreadsheets with while aquiring a bit of spreadsheet literacy before taking on data science courses. And by the way, would you consider knowing spreadsheets as an essential skill to have before starting to use more complex data storage and manipulation tools?