Grapes are easy to train to any shape you want. If it is growing vigorously, you will need to prune about once a week. When they are vigorous they shoot out a cane at each node as they grow. These can be trained off at any angle you want or pruned out entirely. My young potted grapes are growing in every direction.

This link tells you how to make a standard grape in a container.

Here is a link that might be useful: RHS grapes advice