Hey Gents - finally got someone to assist!! Spent 1 hour with him as he explained the workings of a boiler - what a simple bit of kit they are!!! Fixed the problem (gas valve & weak pilot) myself in 2 hours - cost me a couple of pints, a new adjustable wrench & a tinny of WD40 (not needed as it...
Thanks Gents but cannot afford a professional!! I've removed the water & gas section as I've been told it might be the diaphragm thats faulty. Trouble is now two of the six screws bolting the water section to the gas section are rounded & seized (not done by me!!) - I'll try some release agents...