[Grubbypaws]

Eek!

Had a guddle through the window in my potato bag as advised  and put my hand into an ants nest 

What should I do?

[mumofstig]

You could try flooding the bag with water, standing it in a bowl for a little while to kill them, before draining or else buy some ant bait which foraging ants will take back to their nest.

[DHM]

Grind black pepper over the top of the soil, the little * can't stand it!
We've successfully banished them from the house by creating 'barriers' around window and door frames, inside the upvc cavities the windows/doors close into.

I once treated an ant laden planter full of soil to a black pepper 'shower' and the next day, not only had the ants completely disappeared but their eggs had too, the pesky nutters probably carrying them off as they legged it.