books on how gang work in the uk?

Should we be concerned orrrr

calm down its a research project

It's a reasonable concern as you didn't elaborate why you wanted books on this topic.

What is your research project about?

I don't think you're going to find books on this exact topic. If there are going to be books that cover this, it'll be at most a single chapter devoted to it from a book talking about crime in the UK. I recommend past news articles and documentaries you can find

Agreed.

You could also go further and compare and contrast countries that have legalized recreational and/or medical use of marijuana (e.g. Uruguay, Canada, some states in the USA, South Africa). As far as I know, the UK has legalized medical use of cannabis so you could look up research and social impact regarding legalization of medical cannabis on the economy.

You will also need to look at the pros and cons of legalizing cannabis vs complete illegalization. It would also be good if you looked at the differences in legal status for possession of marijuana for recreational/non-medical use, as some countries make cannabis outright legal (zero tolerance policy), some countries hold cannabis as illegal but this is unenforced, some countries hold cannabis has illegal but it is decriminalized, whereas several countries have legalized possession of cannabis.

You should also look at how legalization has impacted the economy in countries/US states that have legalized recreational marijuana, especially legality when it comes to commercial sale of cannabis (e.g. Netherlands might be good).