There are no stations on the Lickey incline - the nearest stations are Bromsgrove or Barnt Green (a few miles from Birmingham).
Other stations where you might see Class 66s include Doncaster, Nuneaton, Stafford, Ipswich, Reading, and several stations in the London outer suburbs. As suggested above, visit the real time trains (RTT) website for a guide to freight (& passenger) services at stations of interest, and note that some freight services only operate occasionally - as required by freight customers.
For example, this is the RTT page for Stafford; change the date and station name as you need.
Remember, safety is important for railway operators, so stand well clear from platform edges, and avoid using a photo tripod on busy areas of station platforms. You will need a ticket (travel or platform) to enter many stations. Do not use camera flashguns/ lights at any station.