Oh dear,
Another sad story,
I'm not prepared to predict the outcome of this one. again we are hamstrung by not having all the relevant details and facts.
Dusty is quite right about your rights under SoGA, BUT it depends on the details of what you were told by your seller before purchase. I'm talking about the nitty, gritty details, and I suspect its not quite as clear cut as our poster has made it read.
Why for example did you have the caravan checked so soon after purchase? Why didn't you arrange for this inspection before purchase?
The phrase Caveat Emptor (Buyer beware) is so relevant in such cases. I have pointed out several times, anything the retail seller prints or tells you about a product must be accurate, But they are not actually obliged to volunteer any information. It is actually up to the buyer to ensure the product is what they want, and it is fit for purpose for which they intend it, so the buyer must ask all the relevant questions to which the retailer is legally required to answer honestly. Unless you ask the right questions, you may not get the information you need.
I cannot believe a dealer would be so daft as to claim a ten year old caravan "was in perfect condition" But if that is exactly was said then you will have a case, but I suspect the seller will have either qualified that or answered the question you asked, but the question you asked may not have required the answer you need, and you may have made an assumption based on insufficient information. Its these details that are so important and missing from this dialogue.
However, if the independent caravan engineers report is accurate and the caravan structure is unsound, it will have to provide evidence the cause of the failure must have been present at the time of purchase, because if the underlying cause is possibly due to misuse or damage since purchase, then the SoGA case will fail.
If the SoGA case is upheld, then it suggests the caravan is beyond safe usage, which is a clear contravention of the SoGA Fit for Purpose, and Free from Defects. I would have little doubt a full refund and all consequential losses should be awarded.
But on the information supplied so far I couldn't call which way it would go.