Well you probably ought to be a bit more curious. Just for starters, there's their economic manifesto, in which they essentially outline their plans to destroy the UK's financial sector. They also want to tax pretty much everything, restrict the number of journeys people are allowed to take. There's even a brilliant bit where they admit that most of their policies are impossible to implement while being a member of the EU, but blithely insist that they will simply reform the EU so that it's more to their liking.
https://policy.greenparty.org.uk/ec.html
Honestly, they are idiots and they are totally fúcking nuts, which doesn't really reflect well on anyone who votes for them.