Turn the cold water off. Do you have play in the WM hose? Take off the hose on it just now.
Ideally the copper pipe and washing machine valve would twist clockwise so the outlet of the appliance valve points upwards, the copper pipe should turn quite easily in those hep push fit connectors.
Pop a couple of 22mm snap over pipeclips where the washing machine and dishwasher pipes could come from, just above the valve in that space to the left of the ISO valves, then down onto the y piece. The clips will help support it all and keep it in place.
Or you could use one of these http://www.screwfix.com/p/compression-appliance-tee-brass-x-x-15mm/24030
I'd just be careful as none of that pipework is clipped so a double valve with 2 appliance hoses could put a bit of stress on the push fit tee. Clipping the hoses to support them would be recommended and it may be easier having the hoses and Y piece into that gap rather than trying to fit them horizontally onto a double valve within the space you would have.
Where is that white pipe coming from/going to??
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local