No you are not, not without ensuring compliance with health and safety, food hygiene, etc, legislation. The second you go from cooking a snack for some mates to charging in some manner or providing a regular supply on demand you go from "private" to "business" as you are providing goods and/or a service, whether that is done for profit, gain, reward or some "superior purpose" is immaterial, you are still providing goods and/or a service and therefore fall under assorted regulations. Plenty examples of people falling foul of such things, as seen at assorted things like village/school fêtes as an example where petty council officials get assorted products pulled because compliance with assorted regs cannot be proven. And since growth, supply, distribution and sales of MJ in the UK, IF it becomes legalised, will mean licencing along the lines of at least the same level as alcohol, and the second any money or goods changes hands in exchange for your home brew you are technically liable for duty, vat, etc, before you go down that line, then any sales of home grown MJ will be illegal unless regs on sales, etc, are adhered to. That's a LOT of paperwork for no reward, and will have to be reflected in your "cost price". Of course, as long as you keep it on the QT then it's unlikely that anyone would bother you, especially when not making a profit. A few close friends who know how to keep quiet, never going to be an issue. Start getting a name in wider circles as someone who does good, cheap, weed, you're inviting trouble, and not necessarily from only plod.