No, adding more points will not help here. If you have brick interior walls, you are going to have significant problems with WiFi coverage. The 5GHz signal the points use to talk to each other will have real problems getting through brick (or concrete, or plaster, etc.)
I would run an Ethernet cable from Bedroom 1 to Bedroom 2 and use that to connect a wired secondary Google WiFi point there. Hopefully, that will provide coverage to the kitchen/dining/reception room (but if there are more brick walls, it may not, in which case you'll need another point in that area, again connected back to bedroom 1 via Ethernet). Basically, you want to build a modest wired network here that's rooted in the LAN port of the primary Google WiFi unit in bedroom 1. You can make this a (small) tree structure with one or more inexpensive, unmanaged Ethernet switches.
Getting coverage to an outbuilding is always challenging, and with your primary in the front of a long house like this, with brick walls, it's going to require something more serious. Preferably, an Ethernet cable from your wired network in the house out to the shed. Out there, you can connect another Google WiFi unit to the Ethernet network. This will let it talk all the way back to the primary so it can join the whole WiFi network and provide coverage in the shed and the garden areas. There are some other possibilities (basically, buying some more expensive point-to-point wireless gear that creates a virtual Ethernet cable without having to run a physical wire). But, the point is, even though a mesh network can expand the usable coverage area, it isn't perfect.
