Hi 24, how are you doing?
You asked about my fave soft drinks - I love the Fever tree 'mixers' like their ginger beer, and tonic water. Really good quality tonic water in a wine glass with a slice of lime feels almost as nice as G&T!
Also there's a French sparkling pomegranate juice you can get at Waitose (called Pomona? Or something?) It comes in a gorgeous old fashioned bottle and looks and tastes divine.
Fentiman's drinks are really good too - they do a 'Curiosity Cola', and if I'm in the right mood I love their 'rose lemonade'. They also make a dandilion and burdock, which is a taste of my chlidhood! 
There's another company that makes soft drinks with numbers - they look v. upmarket with flavours like lemongrass. I haven't tried them yet as I can't buy them round here, but they sell them in Selfridges.
These are not the cheapest, but still cheaper than booze
. Ihave to confess to drinking lots of sparkling water wiht lemon slices in, and also Sainsbos cheap-as-chips flavoured sparkling waters too. I don't like v. sweet drinks, so I don't really drink things like cola. I'm not a great fan of fruit juices or smoothies but obviously there are some gorgeous ones on the market; cloudy apple juice or pear juice are my favourites, which again I drink from a nice wine glass and buy the best quality (still cheaper than wine - and locally produced, so all good!)
I drink lots of types of tea too - current fave is Lady Grey (like Earl Grey with citrus - v. perfumed and light). There are loads of lovely things! 