Is the post-study work visa granted automatically or do I have to apply for it in UK for a Master's?

No, the post-study work visa (Graduate Visa) is not granted automatically - you must apply for it after completing your degree in the UK.

- You need to hold a valid Student visa at the time of application.
- Your university must confirm your successful course completion to the Home Office before you apply.
- You must submit your application before your current visa expires.

The Graduate Visa lets you stay and work in the UK for up to two years after a master's degree (subject to change).