I'm not aware that there are any plans for 'government certificates'. What is about to come into effect is the 'Home Information Pack (HIP)' scheme. (Home Information Packs were originally to be called 'Home Seller's Packs' and you may still this alternative name used)
HIPs become compulsory from 1st June, 2007. From this date, anyone wishing to sell a house will have to obtain a HIP prior to advertising the house for sale. HIPs have to be provided by a qualified and registered Home Condition Inspector (which is possibly where you got the idea of a 'government certificate' from).
The cost of an HIP is expected to be between �600 and �1000. The proposals are far from being universally popular:
http://www.findaproperty.com/story.aspx?*******=5474
Chris
Chris