Returning to cycling after many years out

xf8u
xf8u Posts: 9
Hi, I have been cycling for over 20 years now. Recently, I have got a Mountain bike in addition to my existing road bike, as I enjoy both equally.
What I would like to know is how long after eating a good meal should I go out training.
Also, can anyone recommend some half decent drinks to take with me. Years ago, when I was racing I used to have lemonade/water. I'm sure there is a better alternative these days.
Thanks in advance
Mike