You should most definitely invest in a testing kit if you can afford it (they're not expensive, so should be able to afford it). Ehrlichs reagent is what you want if you're only getting it for lsd, but if you do anything besides lsd consider picking up a different, or multiple, kits. I believe dancesafe.Org is a good website (I think I'm allowed to give you that, in the name of harm reduction. The Ehrlich kit contains hcl, ethanol, and p-dimethylaminobenzaldehyde, which I believe all those compounds are legal in the UK, but double check if you're unsure.