Hi Chumbley! My Aunt lives in Brocklehurst! I think your hole sizes are fine, and the compost a great idea. As for further amendments I would check on GOOGLE for each specific plants requirements. Also make sure you harden them off before putting them out in the direct sunlight. Have fun, Joelle

I assume the 14" x 18" hole is for each vine, not all of them together, right? (It might suffice for one plant only, needless to say.)
You will have to be sure to be water these plants regularly, as their roots will have very limited opportunity to access water on their own, due to the surrounding concrete.

Joelle and ABgardeneer, thanks for the responses. vines planted will see how things go. We are having so much June rain, watering won't be an issue yet.
Chumbley