Immigrationboards.com

I have been looking at upgrading from postal to premium. Just wanted the following clarified please -

1. Can I go to the premium service centre of my choice (Croydon)
2. Can I choose the time and date that I want?

I can't see any of these of the form.

Yes as long as the UKVI agree to the upgrade. They will let you know

I would prefer not to go to a premium service centre but upgrade to a priority service where the application is processed without me being there.

Is this true? I just realised a little while ago. Please confirm