A house survey shows Gas, Electric & Heating to be poor - what should I do?

Ask for the certificates to show when they were last serviced. Get an estimate as to the cost of possible repairs and ask the vendors to reduce the price of the house by this amount (uming you put your offer based on the condition 'subject to survey'). If they won't budge, look for a different house if the costs/dangers concern you sufficiently. Basically, negotiate.