only the trade will buy cars sight unseen

Untrue. I wouldn't buy unseen but plenty of private buyers do

? i certainly wouldn't touch anything motability

Again plenty would & in this case so would I. They are generally well maintained, low mileage 3 year old cars.

My concern as a private buyer would be that I am buying privately & not via a dealer hence Sale Of Goods Act would not apply.

The RAC 1 month waranty is pretty useless as most failures occurring within 30 days would be deemed to be pre-existing (& so excluded). Although given the RAC inspection perhaps this clause would not apply????

It's obviously a broker service rather than car sales & as such I'm unsure it will work; but this is Tesco, the buyers are the GBP & so who knows? I certainly wouldn't like to bet against it