Hi all,
This got resolved with a conversation between our architect and BC officer.
It was agreed that the inner room had 2 egress routes, that were opposite each other, and so as separate as possible. The store is very small, and as it is lower, some of the room will be used up for stairs, leading to less space for clutter. We will need to install a heat detector in the pantry and garage, and smoke detector in the study. It is extremely unlikely there would be fires in 2 parts of the property, preventing escape.
The fundamental principle was agreed on that in the case of a fire, you can turn your back on it and escape another way.... and we do achieve that.
Thanks for all the input... I hope the thread can serve someone else in the future.