It depends on the head shop to be honest. Theres a fairly well know one in manchester central (though I will say no more on that note)
And there USED to be one in a small town in manchester called altrincham, but that place closed down maybe a couple of months AT MOST before it went out of business.
The first place, the one still extant, they carried MXE before the ban, likewise 5-MAPB abd 6-APB, do a decent range of synthetic smoke blends, wippits, as well as herbs like salvia extract and kratom extract etc.
Great place, friendly staff, one guy there always ends up knocking a few quid off for me, or sometimes telling me take it now, and owe me the rest later when you next come back. Even getting a hand-rail up the entrance steps I think, he said he would get it fixed, because of my difficulties walking and especially going up stairs, lol even got given a bag of kratom on my last birthday, when I had been into town and quite literally got stuck, because I could barely move my leg/hip and when I did, it was absolute agony. In all honesty I don't know if I could have managed to get back home witout that.
Staff there are always happy to talk and discuss ideas and suggestions about what to get in, explain more about the products themselves and they actually do take a lot of care to be responsible, won't sell to kids, although in certain cases IMO a bit TOO responsible, E.g manager won't stock benzos due to potential addiction issues (and doubtless a witch hunt trigger were there even one fatality, regardless of how (un)related the person's death may have been to the substances used.
On the other hand, the place that closed down, I'd got a few things from there that I'd looked up beforehand, and then asked about some of them. Woman there really didn't seem to give a shit, and came out spouting a right load of waffle about how she can't discuss the contents of their products (notably when I was looking at some pre-rolled 'joints'. This was about the time some of the 'noids were becoming quite big. Asked her what was in it..and just got a load of evasiveness and refusal to level with me at all.
Turned out there was NOTHING in or on them, no cannabinoid whatsoever. Stupidly enough she gave me a free sample to try, it was, however completely inert.
There is certainly no law against giving solely factual information about the contents (if there had been any that is), telling people how much to take, what to take. I could understand, that people must be allowed to make their own choices themselves rather than be 'steered' into making a purchase of ABC and telling them to take DEF dose etc. etc.
But wouldn't freedom of speech laws not make totally clear that providing information on the contents of a product, particular risks, HOW XYZ works and so forth?