Patio with gravel border

[Mlmorgan]

Hi guys. This is my first post on the forum. The project I'm about to embark on is also my first ever attempt at anything like it so please bare with me, I'm a real novice.
My partner and I have recently moved in to a new property with a fairly large tiered garden. There is a path running around the side of the house that opens up in to a small patio (16 450x450x50 plain grey slabs) that sits just by the french doors at the back of the house. It is my intention to extend the patio by another 30 slabs and to have a gravel border running around the patio. To the side of the house we have an area which is roughly 2x6m2. It is my intention to cover this entire area with gravel and have it meet the gravel border of the patio. Having read many tips on this website I'm feeling just about ready to start work however I have a couple of questions that I am struggling to find the answers for,

Firstly, I'll be laying a sub base around the existing patio for my new slabs as well as sub base for the gravel area at the side of the house. Both these areas are going to be connected and probably dug out to the same depth so should I dig it all out in one piece or am I better off treating the patio and gravel area as two separate jobs and just digging out around the patio first.
I hope I have explained what I am doing well enough for you all to understand. Any help would be much appreciated

[local patios and driveway]

did both at the same depth, the gravel area will need a deeper sub base as you will only need about an inch of gravel at the most. im only replying because you have been ignored. best of luck