I want to Grow a Grapevine in a Container

As above I have ordered a Grapevine "Blue Dream" from Suttons Seeds which I want to grow in a container on a balcony against some black railings which is South-South/East facing and gets full sun for most of the day in the summer and I want to get fruit from the vine eventually... it comes in a 3 litre pot so I don't expect I will be getting any fruit for a few years. Anyway I have a few ideas as to ways of training the vine but need a few questions answering...

What is the minimum size of container I would need to plant the grapevine in? I'm thinking of using a 18"-24" square container and one thats about 18" deep.

What is the minimum size of support I would need for a vine to fruit on? I'm thinking of staking a large fan trellis about 2-3ft wide and 6ft high in the container and training the vine on that or is that too small for fruit production? I'm not really interested in producing masses just a few good bunches for me to um snack on! :D Another idea is to place a 6ft x 6ft trellis (probably bamboo for aesthetic reasons) behind the container and training the vine on that.. I'd like to train the grapevine directly onto the railings but as I'm in rented accomodation I don't want to cause damage to the place and the railings are only about 4ft high anyway.

At the moment I'm leaning more towards the 6ft x 6ft trellis behind the container idea... but any other ideas and suggestions much appreciated!

Cheryl x