Owning your own home

Leasehold question, probably for @danstuff and @BleakRefs :

The agent of the freeholder is doing mostly external, communal works on the block. Part of this work involves doing work on the balconies of each property in the block. The balconies are inbuilt, rather than exterior overhanging. The work involves surveying the balcony walls for cracks and defects, removing the offending plasterwork, then making good. 'then making good' is an assumption on which I bloody well hope I'm right on.

So the question: what kind of permission does the freeholder or their agent require from the leaseholder in order to do the work on the balconies....on an ad-hoc schedule over the course of a month?

• is simply telling the leaseholders they will be doing the work OK?
  
• do they need to be specific about the dates / timescale?
  
• does the leaseholder need to expressly give their permission?
  
• or is it ok for the agent to say 'if you don't give your permission please tell us'
  
  

The question hinges on my assumption that the balconies, unlike say the communal stairwell, are the 'property' of the leaseholder, and that permission is required to 'enter' them.