I might be wrong but there isn't much time to spend this on improvements to the hard infrastructure (eg, runways, taxiways etc), if that were needed surely it would have been thought about before now.
More likely this will cover the costs of bringing in more ground equipment, temporary buildings for crew use, facilities for security provision etc?
To update the above posted yesteday, there's a bit more info within the following
ITV News
You would think that 2.5 months is not a lot of time to complete the types of work mentioned, but we don't know how significant they need to be in reality.