If you are around friends... I have the feeling they wouldn't mind if you left off the bookish-sounding grammatically correct ending of (something like your second example sentence.)
However, your first sentence's meaning almost sounds like this (to me):
If it rains, I plan on going shopping and eating good things.
The second sentence's meaning sounds like this (to me):
If it rains, I plan on going shopping and eating good things.
If you want to keep the context all in check, it's a good idea to end the pattern with , here, though young people probably won't care... and you might find yourself in informal conversations where people break all sorts of grammatical rules. :)