thanks

Only thing I can think of is Gaultheria mucronata "Bells Seedling" which is self fertile - most (though not all) plants with berries need a male to actually produce berries, but this one doesn't. It's spiny, and I wouldn't like it in a tub because its not a particularly neat grower, and brushing against something prickly by the door wouldn't be pleasant, I don't think, but you did say you wanted berries. Bear in mind that anything which produces berries is often prickly, you are restricted to growing something smaller because they're in pots, and that the berries will really only be present for up to 3 months from autumn. There is nothing that carries berries "most of the year" with the possible exception of one or two trees, much too large for tubs.

Thanks

Another excellent shrub is Pyracantha - evergreen, white flowers in late spring, then red or orange berries in autumn. Again, as Bamboo warned, it's prickly!

There are varieties of Ilex (holly) that would do the job as well - and you can get non-prickly ones with pretty variegated leaves, but you need a male holly in the vicinity to get berries.