AAARGGHHH, coolant leak from 1.4 16v thermostat block

Hi all, my 2001 Fabia 1.4 16v is leaking coolant from behind the plastic thermostat housing block bolted to the end of the cylinder head. No problem removing the three securing bolts but how can you disconnect the block from the pipes that goes down behind the engine to the back of the water pump??? There is some kind of sliding clip but access to it is so limited that I can't get it off to disconnect the pipe and I'd imagine it would be even more difficult to get it in position to reconnect the pipe. Does anyone have any bright ideas as to how I can remove and replace this coolant distribution block??? Please???

Cheers in anticipation,

Paul