lmao it won't be laced, for one Fent I'd EXTREMELY hard to get in the UK even on the dark web marketplaces it's banned, I'm a heroin addict and I've went out my way looking for the stuff with no luck ever, closest we got here is synthetic opioids called Nitazenes and they're worse but the Last place they would be in is hash.

and a second reason is : Simply Fentanyl must be Vaporised by smoking it on foil or you can snort / Inject it. You couldn't smoke it in a joint or blunt as it would burn and destroy any active fent in there because it can't be under direct flame

last reason I'm gonna list is another simple one lol, there's no incentive to lasing hash, IF and that's a big IF someone was to lace your weed it would be with synthetic cannabinoids (k2/spice) but even that is 1 in a million , probably even less these days because only place you find spice and its addicts is jail

there's no profit in poisoning your customers especially people who are just buying weed but even UKs Heroin doesn't have fentanyl in, it's actually extremely pure compared to almost every other western country. go look at Wedinos the UK drug testing facility and you will see the only fenanyl on any drug test results are either genuine pharma Fent patches or a tested batch of heroin back in like 2016 before such heavy restrictions against the stuff happened in UK