Originally Posted by
NWIFlyer
You could also consider a website such as justpark which shows private driveways. For 6 days in early October you'd find spaces from £39 which would put you close to a bus route into the airport. Many of the properties also offer a chargeable drop-off service.
Some of the hotels by the airport also offer rates via this site at good prices (c.w. the usual airport parking websites)