This is rarly fatal. Wipe the leaves down with a fungicide so the leaves can photosynthesize at as much as they can. Think of them as a solar panels that have become cloudy with dirt. Reason why I am saying this is that these are young plants that need their leaves to produce the energy and materials they need to establish a good root system. To cut them down could be fatal.

I wouldn't cut it down - mildew on honeysuckle in the UK is common, so I'd use the milk remedy - 1 part cow's milk to 9 parts water in a spray bottle, spray thoroughly all parts of the plant till run off. Repeat regularly.

Thanks for the advice. Have applied first application. Going to Cornwall for a week so fingers crossed after applications it will perk up.