I know there's a quicksave function, but how can I load the quicksaved slot?

As far as I know, there is no way to Quick Load. Pressing F5 to Quick Save is just a faster way of overwriting your most recent save rather than having it's own Quick Save slot like in most other games. So, to load your Quick Save/Most recent save, or to select another save file: press Esc to access the pause menu, select 'Restore Adventure', then 'Load' to access your saves.