Both are correct but they give different emphasis. Both express hope but "to" gives a more positive outlook and a feeling of anticipation. "For" conveys more doubt.
If you use "for", it will be attached to "look" as in "look for" so that it represents a search as well as a hope for something. If you use "to", it will be attached to "forward" as in "forward to" so that it represents anticipation. Here are some examples to clarify this:
"I look forward TO the arrival of spring." (I can't wait! Spring will arrive after some time passes.)
"I look forward TO eating lunch" (I am so hungry! Thank goodness I will eat lunch after time passes. Note: "eating" is a noun, not a verb. "Lunch" is the object of the participle in a noun clause.)
"I look forward FOR better days to come." I am really looking. Perhaps better days will not come. This is an expression of hope mixed with doubt. I am looking FOR those days, but I have to look "forward" because I may not find them. If I said "to", it would have a different meaning. It would mean that I have a positive anticipation of better days to come.