Its actually really easy to fit off a cold water feed for the washing machine. Get a Y-splitter from Wickes and tap kit, take off washing machine pipe, fit splitter, replace washing machine pipe, add tape pipe to other feed, screw tap to wall, and screw feed pipe to tap. Off you go, honestly took me about as long to do that as it used to take me to get the tap adapter on the old tap! And it used to pop off all the time!
I hope you have a non-return valve in there somewhere - its a legal requirement that all outside taps have a non-return valve in line - the kits that 'cut' into the pipe have one built into the tap that screws onto the tap.
There is a non return valve before the Y-splitter, but the tap isnt actually outside, I have it fitted under the sink as the kitchen is on the front so pass the hose through the window. Otherwise theiving scumbags would use my water and I'm on a meter