40 watts on 10 cm on plant

Doubt that you'll get any decent buds from a 40w lights wherever distance to the plants you are going to need a better light to flower the plants I'm afraid And you are slow growing because of your lights not being powerful enough If you want good yealds then you will have to pay for a better light and better equipment but if you are in the UK then it's not cheap for the watts you want to grow and you will also need to get the environment correct as its not just a light and all good it's the whole environment and it's not a cheap hobby in the UK

That light is not well suited for growing cannabis. get it as close as you can. Lots of lights can be "ok" for vegetative growth of some house plants, but the ones that need more intensity and that bloom, its just not enough. I will bloom it will just be a fraction of what it could have been though under better conditions. I would look into investing into some other lights if you want to continue growing and expect anything back in return for your time invested. I used a bunch of pure white 18W strip lights "5x totalling 90W" and has great results before I switch over to a more cannabis focused lighting system. The brand was Sun Blaster and its all that was immediately available to me at the time. Now my setup is much better but I still could grow off of it. Good Luck!

Basically, only 10 watts of power come from each arm. You probably HAVE to place this lamp 10-20 cm close to the plant for it to show any effect at all. Definitely not harmful. In fact, absolutely necessary. Happy Gardening 😎