with only 800 miles of riding you really are not going to see a dramatic improvement... somethings take work, 800 miles is couple of weeks worth of work... how much can you improve in that time?
If you're just starting out, 800 miles is more than enough to improve significantly, especially if you're not starting from an endurance sport background
If you can't average at least 25 MPH solo, don't go to Europe.