Contacts: can one organisation be a 'child' of another?
What I would do is:
- configure a new contact type 'NHS Team' based on organization
- cofigure a relationship type between organization and NHS team
The standard relationship type 'Child of' only works between Individuals, as you can see in the configuration of the relationship types.

If this is gobbledygook for you, I'd recommend reading this: https://docs.civicrm.org/user/en/stable/organising-your-data/relationships/