I happen to disagree about Halfords stuff, they sell some good, really underrated products. For example, AG SRP and EGP are great, especially considering they're off the shelf products, and they are often overlooked or avoided as they're available from Halfords. Likewise, Halfords sells Zymol Natural Car Wash which I really rate and Megs Nxt Generation Speed Detailer is pretty good too. I have found Halfords own brand Intensive Glass Cutter to be good, as have many others, although it doesn't beat Cerium Oxide for removing rain repellent etc, even when CO is applied with a MF - infact Cerium Oxide is the only thing I've found that will remove some repellents. You can even pick up a pretty good mitt and drying towels there.
Overall Halfords has less choice than any online detailing shop and may even be slightly more expensive but I certainly don't think it needs to be avoided.
.... and this is coming from someone who really doesn't like Halfords!