I'm not sure you're supposed to share these codes around (it is probably single use only anyway) and morally I don't think I would use it. I can tell you about my experience with Bremont which explains why I don't think what you are doing here is entirely fair.
About 18 months ago I took part in a Bremont survey for which I received a voucher for £25 off any Bremont purchase. At the time my watch budget was a bit limited, but I wanted to use the voucher. The only things on the website for 25 quid or thereabouts were a keyring and a watch tool. The watch tool was out of stock so I emailed Bremont and told them that I was unlikely to buy one of their watches any time soon and couldn't reasonably use the voucher before it expired, could they help in any way? They said of course, don't worry.
Four weeks later a package turns up with a watch tool from Bremont and a note to say they hoped I would one day become a customer...
I will one day, but in the meantime I'm not going to take advantage of a relatively small British manufacturer who give good customer service.