I don't think it matters where they come from, the principles are the same for a given variety. I've had some reasonable plants from B&Q, also one dodgy one, which I've taken back and got a full refund. I would (and do) do this with any supplier, a plant should be fit to grow. Don't worry about a receipt - make a fuss if necessary, you don't need a receipt if the goods aren't "Fit for purpose"
I agree with Bodolph, even if they say self-fertile, they will always perform better with another pollinator nearby. If you don't get enough info for the variety you have bought, look it up - I tend to use the info on Buckingham Nurseries and Keepers Nurserys website, but the site shown is good and clear in my opinion.