In England, the contract is between NHS England and the individual practice. The vast majority of practices are run as businesses with the GPs as partners who share in the profits of the practice.
The contract will define minimum outcomes, and may well define core hours M to F when the service shall be accessible, plus minimum service offerings, such as nurse-led services.
Practices can also opt in to agreeing additional services for which they get extra central money, for example flu jabs for senior citizens at risk.
No, you can't see individual contracts with practices.
What did you specifically want to know?