Yes I find they help, especially on hot days.
Their powder / energy drink is good too, I make up a bottle of that for longer rides, I really like the tropical flavour.
They make several mixed trial packs (tabs, powders, gels, and depending on the pack, protein shake, energy bars). You can pick them up in Holland and Barrett,
Halfords and sometimes Lidl, and the box comes with a free 750ml H5 bottle, often for not much more than the cost of a bottle itself so it's worth it just looking out for them when you need new bottles.