Lillie
I have had them too - they are fruit flies apparently and come out late August September

I had left a wire scubber in the sink with a tiny bit of food on that they were feasting on it!!

Now keep all friyut in fridge etc

Check to see if you have anything rotting -can be plants ( roots /veg) or food and chuck it out!

I bought fly spray but they just fly off some where else!

They drive you scatty!!!