This one is Download and it says DRM: Steam. I assume that means you download it from Amazon but it works through Steam, I guess?
Edit: Sorry, just realized you're UK. Anyway, maybe someone else can benefit from this sale.
I see that the Amazon.ca version doesn't have a PC download link but if you have a giftcard, would you just be able to use the US PC download link? http://www.amazon.com/2K-Games-41071rderlands-22-Borderlands/dp/B008ALUBYQ/ref=sr_1_1_title_3?s=videogames&ie=UTF8&qid=1343155539&sr=1-1&keywords=Borderlands+2
This would allow you to get the pre-order bonuses, use your amazon card, and avoid shipping and waiting all together. Might be worth looking into how their download center works.
A point to note is that since this game uses steamworks, amazon will just give you a key and a link to their download store. You can just activate the key on steam and download from there, having only used amazon to get a game key and pre-order bonuses.