I think those are fungus knats. You can use the mosquito dunks to kill them. I don't know where you could purchase them in the UK; maybe at a garden center?

Hi Camellia, thanks for your reply. I've never heard of a mosquito dunk lol. I thought those gnats normally hung around in really moist soil which this isn't, however they are about the right size for them. Maybe someone else may know what mosquito dunk in uk is lol.
Kind regards
Averil

I thought it may help to describe mosquito dunks a little more. Do you have a product in UK that is put in outside containers (bird baths, fountains) etc. They are usually rings that dissolve when put in water and they ward off Mosquitos. Well this product can be crumbled in your watering can and it prevents fungus gnats. HTH !

Averil...Sounds like the soil is staying too wet.

Let soil dry between water...fungus gnats appear when soil is wet for prolonged periods, and air is too warm and dry.

Is it possible to up humidity? A rotating fan circulates air. Unless it's warm enough to crack open a window..there's nothing as healthy as fresh air. For humans and plants.

What about soil? Is it well-draining? Heavy, wet soils invite gnats, too. Toni

Mosquito dunks contain Bacillus thuringiensis israelensis, which is what kills the larvae of fungus gnats. [A different type of Bacillus thuringiensis -- Bt kurstaki -- kills caterpillars; it won't work on the gnats.]

Thanks everybody. No I've just asked the other half and we haven't a clue on these mosquito thingummybobs lol..I shall take up the advice of author I think. I will hang it above the kitchen sink and that way it will get a bit of warm steam and make sure a window gets opened for a while every day and see how it goes on. Thanks everybody, you are always so helpful. Take care all
Averil x