4g / 5g home internet

I have set my dad up with Huawei b311 router & smarty SIM card on the 120GB - £12 per month offer.

This works a treat for him as he only emails, browses & watches a few YouTube videos.

I was thinking of doing away with bt line and going onto 4 or 5g for my home internet but I am worried if it would work as my usage is much higher - I am a regular streamer and binge watching can be quite common.

On the smarty unlimited package are there any fair usage caps or restrictions with using the SIM perminantly in a router?