For the greenfly you could try just using the hose to spray them off with water. A good blast with the hose will usually take care of them if you keep at it every couple of days for a while. They don't climb back on the plants.
You could also try soapy water or Neem oil.

I personally dont use anything, I just let nature do its thing!

I use soapy water on all outdoor plants and on food plants.
I must admit that I do use a chemical on the ornamental alpine plants and bulbs in the greenhouse as I want immediate results to prevent the spread of any virus infections.

I try to always use the hose and or soapy water and my hands.

Soapy water mainly and for slugs, going out at dusk and squishing them.

I am planning on using garlic and soap as a pesticide in future but have not tried it yet.

Soapy water so long as you are using an Eco friendly washing up liquid...

Me too, Donna. Try to use as little insecticides as poss. because you'll upset and kill the good insects as well if you use an insecticide. Get the hose out and give them a thorough shower bath!! Annie (Cumbria)

If I have probs on my veg plants, i spray with garlic water, I personally don't go with soapy water on edibles. For non edibles I use a tomato leaf tea diluted and sprayed on.