lost keys euro lock help needed please?

Just wondering if someone can help, I have lost the keys to my upvc back door about 3 years ago, so secured alternately, but as the door is open I'd like to replace the lock. The lock is a euro type design so I can't take old lock out without the key. I have taken the handles off and the screw that holds the lock in place out of the side of the door. I know I could attempt to drill out the centre of the barrel but as I have to replace the assembly and don't need to open the door can I just get a wrench on both sides of the protruding cylinder/housing and if gently turn in opposite directions the cylinder/housing should snap in the middle enabling the two halfs to be drawn out at either side and then a new lock can be fitted without damaging the rest of the door assembly (hopefully). Sorry but calling out locksmith is not an option financially and an old door with a lock is coming up. Thanks in advance if anybody can help cheers.