All ant nests have “flying ants” in them. They are the breeding males and young queens which tend to emerge from the nest “en masse” when the conditions are just right. If they are in your house, the chances are you already have established nests in the brickwork or foundations.
The council pest control is usually very busy this time of year and there is probably a couple of weeks waiting list. There are private companies who are usually quite reasonably priced though.