On the sale of a commercial property the vendor will be required to complete a Property Information and Fixtures and Fittings form that will require completion if the title to the property is freehold and a further form if the title is leasehold.
With a leasehold property one of the main reasons for delay is the collection of information that should have been supplied by the landlord e.g. annual accounts, invoices for ground rent, service charges and buildings insurance details.
If this information is not available from the vendor, then there will be a delay (and a cost to the vendor) whilst it is obtained from the landlord or their managing agents.
For freehold property you will be expected to produce guarantees or warranties for any work undertaken at the property and in addition any required planning permission, building regulation consent and completion certificates supplied by the planning authority.
Delays can be avoided if this information is collected at the earliest possible stage, perhaps even before the property is placed on the market.