Cliff Crooks in blackburn deliver gas bottles too they deal with homeheat gas - quite popular & recommended 01254 50189
I used to work in the gas bottle & heater industry & they are safe as long as u dont put anything near the heaters whilst on, they need plenty of ventilation, have purchased a new heater or least had it checked out which the above can do for u otherwise i wouldn't recommend u use it certainly without having the heater checked or profesionally cleaned out for you - the flame from the jet should not be a yellow colour nor an enlarged flame - thats a warning sign its not right - it should be blue colour & small from the jet inlets below the tiles. Best bet is to stick to getting a brand new one [least u have guarentee on it] or a recon one from a reputable gas bottle/heater retail outfit, also no harm in purchasing a carbon monoxide indicator/alarm just to be extra safe.