When you click on the Contact my GP button from your practice's welcome page you will be taken to the to the PATCHS login page.
If you've registered for PATCHS using NHS login you should click on the Continue with NHS login button to log into PATCHS. You can find out more about NHS login here.
This will take you to NHS login where you should login with your NHS login credentials.
And when you've successfully logged in, you can make a request for yourself or someone you care for from the How can we help you? page.