What's an Acceptable offer

Waiting to sell a house at present,at what point do you say this is the value the market is willing to pay and Accept....is it after 10 viewings,5 viewings what the auctioneer tells you etc?

Usually the estate agent will know how much similar properties in the area have gone for and how many people were bidding on them so they'll give you an estimate with that in mind. They usually put it on the market for a bit less than what they think its worth to get people bidding.
Its really up to yourself. If you get an offer you think is good take it or hold on for higher. It could depend on whether you're lookiing for a quick sale also.