Purists will tell you not to trade the H&S until the neckline breaks. I tend to prefer the outcome of looking for a nice reversal on the right shoulder, because you're already in a zone of resistance as proved by the left shoulder and head. If you do see a good reversal pattern at this level, you have a good chance of returning to the neckline as an initial target and an even nicer reward if the neckline breaks and you head further down to confirm and complete the H&S pattern.
In the case of EURGBP I think this ties in well with a period of likely uncertainty for the EU, which is likely to cause headwinds for the Euro and possible a flow of capital back towards the pound as the predicted brexit armageddon continues to fail to occur.