Hello and thanks for using Just Answer.
My name is ***** ***** am happy to assist you with your enquiry.
Landlords must consult the Leaseholders if these works/repairs will cost over £250 for any one leaseholder (ie if there are 3 Flats and this work is going to cost over £750).
This entails the Freeholder serving what is called a Section 20 Notice, and will normally include estimates of the proposed works and allows the Leaseholders to object if they feel the quotes are too expensive.
If consultation is not undertaken, the landlord may not be able to recover costs over £250 per leaseholder.
If the work is under £250 per Leaseholder, then the Landlord can just proceed and get the work done and bill the Tenants, via the service charge.
I hope this assists and sets out the legal position.