I would go for violas, the smaller petals cope better with bad weather, mine flowered in containers, all through winter.The ones I sowed by seed last summer came in to flower in March and have just finished flowering. I am sowing seeds now but never seem to get the timing quite right and end up buying in at the last minute.
Combinations are quite difficult as bulbs can over dominate or produce lots of leaves and few flowers, you are often better off doing a basket of just one plant.
Trailing Ivy is hardy, but when it was windy the baskets got knocked around more so it depends how sheltered they will be.