If you buy from a company trading while in administration, the supply of goods is the responsibility of the administrator, if something goes wrong and you don't get the goods, they'll refund you for the error, you won't join the list of unsecured creditors. The supply part is more secure than if you'd bought the week before they went into administration. Warranty issues in the first year ought to be fairly straightforward, you by-pass the retailer and go to their supplier, or manufacturer. In theory, you have the same consumer rights, though obviously it isn't as easy to exercise them. I don't know how that works with own brand stuff, where effectively the retailer was the supplier. Warranties beyond the statutory is probably more complicated, I'm guessing it depends on who made the offer.
Buying liquidated stock is something different, I don't think you have any rights beyond it being as described. If it does head into liquidation, I'd expect some bargains from disappearing brands, less so for any other stock.