Camping at Lake Bala in June?
It's "No-See-Um" City!
They'll eat you alive if the wind drops. I'm taking a gallon of Avon "Skin So Soft". It's a good repellent, doesn't smell that bad and, in an emergency, can be used to waterproof your boots. ( not recommended for lighting the barbie, though).
Don't worry. I won't forget the beer.