From that site:
(An expert report that complies with CPR Pt35 will cost a couple of hundred quid - and it's Small Claims so the ability to reclaim costs are very limited too)
Six months or more
If a fault develops after the first six months, the burden is on you to prove that the product was faulty at the time you took ownership of it.
In practice, this may require some form of expert report, opinion or evidence of similar problems across the product range.
Find out more about how to return a faulty item and claim a refund, repair or replacement from a retailer.
You have six years to take a claim to the small claims court for faulty goods in England, Wales and Northern Ireland, and five years in Scotland.
This doesn't mean that a product has to last six years - just that you have this length of time in which to make a claim if a retailer refuses to repair or replace a faulty product.