One popular and free online source of dividend forecasts is DigitalLook though it’s not the one I use.
http://www.digitallook.com/
And as an example, looking up BP there shows the following
http://www.digitallook.com/equity/BP
I point out that all external forecasts of dividends and eps etc. carry a fair degree of unreliability and not only that, they often vary between the sources used. I have no reason to believe that my source is superior to any other.