Okay so they h202 arrived, but after a think while at work today I have decided I am going to try some more organic methods of controlling the problem first.
I have ordered 100 liters of Perlite to be delivered, along with some sticky traps so hopefully I will be able to break their life cycle by covering all the plant pots in the house with a 1/2 inch of perlite and use the sticky traps to catch the adults.
If they don't work, I will get some mosquito dunks and use them with water as a drench.
If those don't work I will try SNS-203, however delivery to Scotland costs 150.02 USD.
Fingers Crossed the above remedies will have a good effect
The sticky traps do little to control the g nats...IMHO, they serve more as to an indicator of the insects that are present in your garden!