I think four years was a very harsh sentence. I think prison was the right sentence but I don't think four years is especially proportionate.
However, she would have been aware at the time that she was committing an offence that could result in a lengthy sentence, so that was a risk she chose to take. And I couldn't give even the tiniest of shits that she's going to miss her brother's wedding. She made her bed and she can lie in it.
I care a lot about the environment and I have sympathy with the actual cause that organisations like JSO and Extinction Rebellion are fighting for. But I think they're probably doing more harm than good with their particular tactics at times - when they do things like this, they actually distract people from the core message.