Sorry, I read this as the person selling the people carrier noticed that the Almera needed welding - correct?
Realistically, for you to get your money back on the Almera, you would need to be able to prove that the person you purchased the vehicle from was aware of the pre-existing damage, and in turn did not tell you about it. Realistically, you've not really got much of a chance unfortunately.
In regards top doing a HPI check on a vehicle, this will only show if a car has been written off, stolen, or stolen and recovered - it won;t show if it has been involved in an accident where an insurer has repaired it, nor will it show accidents that did not go via the insurer (for obvious reasons). We have our own internal industry databases to show if a car has been involved in any sort of incident, but it not something available to the public.