What is wrong with my vine?

Hello all,

A new member here and I hope I have the right forum area for this. If not, please do direct me to the right area of the site.

I have a grape vine growing in a pot (a good 500mm cubed) against a south facing wall and I live in the south east. It has been doing really well, but for the last 2 years it starts growing well and then the leaves start turning yellow and dropping off. I have photos attached, I wondered if any of you with far more experience than me knew what it was and if there is a cure?

I note that some of the leaves have small black dots on them, almost like some form of insect dropping possibly?

 

The black bits could be caterpillar droppings.