what's UK Costco's return/exchange policy on defective laptops? Is it the same as US Costcos? (which is 90 days)

The airline lost my carry-on with laptop inside. Entirely my fault for agreeing to have it checked and leaving the laptop inside.

I'm at a hotel near Gatwick and there's a Costco not too far from here. I plan to go there tomorrow and get a replacement laptop. I don't know where else to buy computers, so I figure that Costco is the safest place. I have a US Costco membership card.

Also... I assume that laptops sold there will just have the standard UK plugs. I just have to get a UK-to-US plug once I'm back in the US. Is this correct?

Thanks!