I agree with some others, if you are on your bike all the time, no need to train. Sounds as if you are young and relatively fit, no need to train. I did my first tour this summer. Just a week. Had a place to sleep each night so my load was kind of light, just two panniers with food and clothes and a few other things. I commute to work 18 miles each way a couple times a week and ride to school a few times a week.
Just remember to slow down on tour. Don't be in a hurry. Get some gears so you can sit back and just spin up the hills. Stop frequently to enjoy the scenery or eat a little something and you'll be fine.