Depends on the size of your car(s)!

The bricklayer should be able to work this out according to the door size and frame width.

I think the smallest size shower is 700 so would probably use that as a minimum although that's for a fully enclosed shower so you could potentially go a tiny bit smaller if stuck for space. It does also depend on your family's size though as to what is comfortable for everyone. I'd also include the niches for shampoo bottles etc if possible

Re-cupboards and storage, it depends on your style. Have a look at Ikea Pax, you can probably put in a corner unit............I don't know what your dimensions are. but they do allsort. The doors with the cork finish are good for a lounge as they make them look less like a wardrobe. Also, you could have one door with a mirror on it and cut down on wall space for a mirror elsewhere. Same with the desk area. If you have an office in a cupboard you get extra storage, you can also close the doors to make it look really tidy.