I found the Brewdog Soft drinks! Only available through Tesco:
Four flavours of BrewDog's POP Soda sub-brand have launched exclusively into Tesco
www.thegrocer.co.uk
Edit: the link may ask for a subscription but if you Google 'brewdogcola' it's the first link and the whole article is available.
Cost is ÂŁ4 for six 330ml cans. Standard size soft drink cans, price is on a par with six San Pellegrino of the same can size, so not unreasonable price wise.
Will I drink it? As a soft drink person I am curious to know what they taste like, but they're never getting my money. I will see if I can find any ingredients listed on Tesco, that will probably give me an indication whether I would like it.