Can I use different yarn for my pattern?

I’ve found a pattern which uses Rico esign, Mia yarn. I’m finding it quite hard to get hold of (i’m in the UK) and I don’t think I like the look of it anyway.
Can I use a different yarn so long as it matches the same gauge?

As long as it has the same wearability facets I think so, yes. By wearabilty I am meaning that if the item is supposed to stretch and the original yarn did that then you will need to look for that quality as well as gauge in an alternative.