It will depend on the wording in the lease. If the repairing covenant of the landlord allows this and to recover costs then you could be obligated to pay.
It is difficult to say on your typed extracts. I really need to see the lease to comment upon it.
There is no conflict between 4 and 7. The purpose of the clauses is to allow the landlord to inspect, serve notice if tenant is in default of its repairing obligation and to undertake works itself if tenant fails to remedy breach.
The repairing obligation may be within a service charge provision.
If there is no repairing covenant then you cannot compel the landlord to repair the roof.
Like I said I really need to see the lease to comment.