One idea is to consider regional airports. Here's their list for UK and Ireland Regionals with information at the links:
* Generally, flying in and out of regionals is more expensive. There are exceptions however, and especially with pricing specials you won't add much to the trip.
* Regional travel may subtract a car leg or add a flight leg. My personal preference is driving for a few hours rather than flying for one hour plus check in times, etc. I've seen people plan trips where they wind up flying very short distances and probably would have been happier and more comfortable driving a bit extra. On the other hand if flying to the regional airport costs the same and avoids a rental car or extra time you may save time and money. Some folks hate big city driving and Regional Airports can be a great way to avoid that when your destination is not a big city.