Newbie, just a query re different passes. Thank you

That entirely depends on what you intend to do and how much and where you intend to travel.

If you're only going from the UK to Switzerland and then travel around there, you could think about a Swiss Pass and normal tickets from/to Switzerland:

https://www.swiss-pass.ch/

A Swiss pass is valid on more rail lines and not just in trains but in all public transport. Only some tourist lines are excluded but there's often a 25% or 50% discount.

Validity of Swiss Pass:
https://shop.swiss-pass.ch/assets/docs/Overview_Map.pdf

Validity of Interrail in Switzerland:

https://www.sbb.ch/content/dam/infrastruktur/trafimage/karten/karte-geltungsbereich-InterRail-EuRail.pdf

Thank you.