Get a cheap 1-2 tb drive and start dual-booting with whatever system you're running now. This way you can play around with different distros while retaining your current settup to fall back on!
It wouldn't be the most ideal, but you can dual-boot with an external drive. There are external SSDs that are meant for running programs/games off of them, and would look into those for best performance.
Alternatively, if you have plenty of unused storage on the laptop you can partition some of that for use, but a second drive is usually preferred.