Leave the M23 at junction 9, following signs for the airport. Head straight over one roundabout towards the North terminal, then take the third exit, signposted Long Term car park, at the next. You'll pass a petrol station on your right, then take the third exit at the next roundabout for Perimeter Road North. There's another roundabout a kilometre down the road where you should take the left exit, then the first turn on your right. The car park will be on your right after 100m.