For some time I was on a chromebook. These things have meager 16 GB SSDs as Google wants you to do everything on the internet. That's great but I don't always have an internet connection! So what to do? Well I loaded a 64 GB SD card up with music and movies and plopped it in the computer. It never came out. Worked great.
When you are at home, you can rig up something more permanent. External drives that connect via USB 3 or Thunderbolt are so fast that they are virtually indistinguishable from internal drives. Keep your core apps on your laptop's internal drive, toss media onto an SD card and leave the big stuff (including other apps and things) on the external drive at home.