Be careful with discount vouchers etc as legally shops are not allowed to offer discounts or offers on first formula. So £10 off when you spend £50 etc won't include first formula. It's the same with things like club card vouchers, boots points etc they cannot be used on formula.
The law is designed to avoid any sort of promotion on formula, to avoid advertising it as an alternative to breast feeding.
I've never had a problem with buying first formula this way and have done it in all of the main supermarkets; tesco, sainsbury's, waitrose, ocado and coop. Have also used my Tesco vouchers for this purpose. From what I understand, the t&cs for monetary value discount (e.g. £10 off) have not included any restrictions on formula. The law more applies to specific promotions, but I could be wrong and have just been lucky!
In terms of cooling a bottle, about a half hour at room temp should do it
they do like to keep us on our toes! Xxx