I'd suggest not to buy an interface, if the objective is just to practice at home. You'll need a proper DAW, to get decent AMP simulations. E.g. I use Logic Pro X's amp models when I use my Scarlett 2i2 to record stuffs. If you're on Mac, you can try out garage-band too, which is free. But I never tried the amp models in it. An interface becomes essential if you're serious about recording and music production.
As far as my experience goes, Roland isn't suited for heavy metal. I bought a Roland Cube 40 last year. But even the extreme preset tone was pretty anemic for heavy metal, so I sold it. I'd rather suggest Fender Mustang I/II if you're on a tight budget. Although my Mustang II broke after 2 years of usage (that's when I bought Roland, but alas...). Ultimately, it's better if you go to a music shop and try out different amps, as what might work for me, might not work for you.