It's a dilemma because you know your stuck with it for years once it's on. We recently painted our cedar exterior. Started by agreeing on a general colour and then buying a series of sample pots. We finally decided on dulux colour bond dune. Amazing in itself as we rarely agree haa. It was a nice mix between beige and grey. We bought the 10 litre tin and went to work. After completing one wall I thought the paint was taking a while to dry as it wasn't getting as dark as the sample. My husband thought it was because of the lighting. I took a piece of wood and painted the sample which we loved and the paint from the 10 litre can together and yes they were a different shade. The hardware store had accidentally mixed the sample pot in double strength. It was all fixed up and we really love the result. So it was Dulux Colourbond Dune. I think it would be perfect with your roof colour.

Thanks for the photo's it really show's what should be painted with what, just by looking at the first photo looking towards the stairs, the painted bulk head would really bring the ceiling down and then again the second with the bulk head above the external door, wall colour is the right choice for me. cheers

As a former art restorer and now retired I am proficient at mixing colours, I agree with the two above me taking the pillow case is a good idea and the other thing is to do is make sure that the grey has a blue touch as some have a green touch or a brown touch etc so it is possible to get the wrong mauve grey which has a red/brown base to the black and white to achieve the mauve/grey, overall the paint store have people who will help you pick the right colour as often a colour on a small sample looks a lot different when applied to a whole wall. Good luck

some photos would explain the dilemma