Not been there is a while, but "The Airport" pub is a great place to consider parking while waiting to pick up friends and family, before you nip to the terminal to pick them up.
Yes you have to pay for parking there, but you can enjoy a pint or a soft drink while waiting in very pleasant surroundings. - £1.80 for an hour, £3.50 for two hours or £5.40 for three hours, surely cheaper than the short stay?
Our Parking Guide at The Airport Pub
Considering they are right on the airport property, don't think the parking fees are too bad, very nice inside and amazing views of the runway!