Compliance with Landlord/Freeholder requests

Other

1) I own a flat and my landlord/freeholder stipulates that if you want to rent it out you must show (and pay for) them to approve the tenancy agreement. I own other flats and this doesn't apply to those. What would the consequence be if I didn't do this?
2) I would like to build a 'demountable' wall to make the dining room into another bedroom. I'm concerned that the landlord/freeholder may refuse this and/or ask for a payment for consent. Again, what would be the consequence if I didn't do this?
If anyone has experience of either of the above situations I would very much appreciate your advice/views. Thank you.