The need will probably be to save money in the very short term.
Closing bases costs more in the first few years than it saves. Short term savings (for the RAF) include:
Fuel costs (fly less)
Wages (if you can get rid of people without it costing too much, reduce recruiting, increase natural wastage by not signing people on, etc)
Reduce spending on short term lead items, spares, etc.
Cancel programmes where spending has not yet been committed.
See post 69 by Vin Rouge in the "Will the Tories axe the RAF" thread, it will give you some idea of how much pooh we are in as a country!!