Here are some printables to turn those fingers green!  Along with them, you might want to check out: 

The excellent RHS website for guidance of when and how to plant things, as well as other awesome advice. 

Wildlife Trusts has some great advice about how to make a Hedgehog Highway. 

Friends of the Earth has a great list of pollinator friendly plants. 

The RSPB has a fun activity making a bird feeder from recyled materials. 

If you don't have a garden, check out these nuggets of wisdom from the Spruce about growing veggies in your flat.