Actually it is legal to own seeds in the UK. That's why you have so many amazing seed banks in the UK. They're pretty much the best. The law due to how it's worded allows for seeds.
Someone said just go to holland. I don't know about the whole country, but Amsterdam isn't that great at all. Cannabis isn't laced in the UK. That's a myth.
Completely unflushed weed, meaning if you don't give hydroponic weed any period of time where you only feed it water before harvesting it, will seem like it is laced, but its not, just impatient or completely inexperienced growers. It won't be very smokable. It will get hard and harsh when you smoke it, not light properly, sparkle and crackle when lit, and taste nasty.
That's the beginning state of most weed, before its been fed water. There's absolutely no reason for them to lace the weed. Why would they ruin their own product for no reason? Higher quality products command higher prices. But turnaround is also an issue. Almost everyone is going to flush for at least around a week, but sometimes the growers just pluck the flowers even earlier than that. Needs far more than a week. This is the problem in Amsterdam. They take a lot of short cuts, because they know they can get away with it. Gotta find the right places. Quality of Barcelona cannabis clubs so much higher than the ones in Amsterdam.
