Agreed, we have some of the most expensive airports up here - bargains are rare flying from Edinburgh, Glasgow and Aberdeen. We have previously travelled down to Manchester (mainly) but also Newcastle, Leeds Bradford & Liverpool to get a better deal.
We get hit early with school holiday price hikes but luckily Scottish holidays differ from England's so we can head south in our school holidays and save a packet. With the twins that makes 4 of us and savings have been up to £220 per person flying from Northern England (where the school holidays haven't started yet) rather than Scotland (in school holidays). That's £880 to drive for 4 hours, no problem. We do need to stay over the night before if it is an early flight, or when we return if it is a late flight, but it is normally easy to get a couple of Premier Inn rooms for £30-40 each so we are still £750+ in credit.
On the first week of School holidays in Scotland, if you fly from Newcastle you won't hear a Geordie accent, everyone in the car park bus, check in queue, bar, on the plane is Scottish
Next year we travel more just the two of us, so the savings are halved - but also we can't be ar$ed with the miles and overnight stays (it also means losing one more valuable holiday day at work) so we have got up early (we = me) to get the outcoming Easyjet flights which suit us well at the price. They have doubled since and I would consider driving to Leeds Bradford rather than get ripped off (my company's head office is in Harrogate) but luckily we (me) were up to get a good deal.