Two storey extension

We need to know whether a two storey extension is possible in the house we're in the process of buying. We have the floor plans and photographs but access to the property is tricky as we're in the process of buying it.
Is an architect/builder out there able to tell us if an extension is physically possible from just that amount of info? If so, we'd then love to dicuss drawing up plans in order to obtain planning permission.
It would be a very basic design as all we're after is a dining room for the ground floor and a basic bedroom for the second floor - essentially two rectangles!