4 week prep for 300+km

I’m returning from an injury and have 4 weeks until a decent weekend group ride. We’re taking in 300+ km and over 3000m climbing.
I’ve ridden 200km a few times before amd have an ok base level of fitness.
Unfortunately I’ve only been back riding a month after sitting out for 5+months with a back complaint.
What’s the best plan to get me ready with 4 weeks to go?

Take a look at the building blocks, there are 3 and 4 week options, where you can select which metrics to work on. Given that you’ll likely be riding a tempo pace, an FTP or Tempo block would make sense.