You would need to look at the lease which is the definitive document.
Your property would normally finish halfway through the floor joists and halfway through the ceiling joists.
The floor plan will not normally assist somewhere there will be a description of either the Premises or the Property or the Building or the Leased Property.
If there is no mention of the loft space them by default, it is not included and you would need the freeholder to grant you a lease of the loft. Very often, they would do so if you assumed responsibility for the roof. However they are under no obligation to do so at all or at any price. You cannot compel them to do so and you cannot compel them to do so at a price if they simply don’t want to.
Can I clarify anything else for you?
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