I might be missing a few things here, but my immediate thought is "wanna be a better bike rider? ride your bike".

Don't get me wrong, I am a huge fan of x-training and think it's generally an excellent idea in the off-season.

However, as a new cyclist, if you live where the roads are currently rideable, the most important thing for you is saddle time. Indoor workouts on the trainer would help, but they are not as useful as "real life" experience where you also develop bike-skills.

How is your tour structured? 350 miles each week? What's the longest one-day ride? The most challenging climb on the route? You'll need to know these things and prepare enough so that you will be comfortable by the time July arrives.

Give us more info and perhaps we can help you a bit more...