To keep ants out of pots, raise the pots on something so that there's a gap between them and whatever surface they're standing on - use pot feet or bits of old roofing slate, whatever. If the pots have active ants nests inside, you will have to turn the plant out, get rid of the compost (you might need to soak it off in a bucket, this will at least get rid of the ants) and then repot in fresh compost - make sure the drainage hole is not blocked, and you can take the precautionary measure of using either some weed membrane, or half a jeycloth, laid over the hole to discourage ants from entering. Then stand the pot on whatever you're using to keep it off the ground beneath, leaving space and air between the pot and the ground.
Ants on stems and foliage are there because of aphid infestation - the ants harvest the honeydew from the aphids, but do not actually damage your plants at all. Treat for aphids.

Thank you so much Bamboo, I figured the aphids were feeding the ants, I've stood and watched them all last Summer! lol. Really looking forward to (hopefully) ant free pots, mebs get some fruit this year. Again, thanks so much, really appreciated. I think I love this web site!