Thanks for your question. I hope I can assist you.
There is no statutory provision requiring a flat to have a particular flooring laid.
It will depend on the structure of the letting arrangements. have the flats have been sold off or are they in the ownership of the freeholder?
If the flats have been sold off there may be a provision in the lease, requiring the floors to be carpeted. It will depend on the wording of your lease if you can 'force' the landlord to enforce any covenants or regulations contained within the lease of the first floor flat.
If the landlord lets out the flat on a tenancy then you will need to raise the issue with your landlord that the noise from above is affecting your business, this will then be down to the goodwill of the landlord to resolve the issue.
It is debatable whether the noise constitutes nuisance.
Do you have any further questions or queries.