Appointments+ how to add padding time between appointments

I am currently one person offering a service of 10, 20, 30, 45, and 60 minute phone consultations. My first question is about creating the 45 minutes since the minimum time base number it seems is 10, and also I need to add 10 minute buffer time (padding time) between each appointment so I can get the materials I need ready for the next client. How can I do this?
I know there are many other people who have asked the question in the past but the solutions seems to be tailored to what exactly they need for their service so i would like to know what the solution would be for mine. I'm not a developer or designer so if I would need to add code if you could explain exactly where I need to go to paste the code you give me that would be great, thank you!