How far are you wanting to travel? Direct trains or not? There and back the same day?
West Midlands Day Ranger at £28-80, if still available, might be the ticket.
Special offer: West Midlands Day Ranger. The portal into UK rail travel, including information on ticket purchase and promotions, train times and delays, and more.
www.nationalrail.co.uk
Could get to Northampton via Rugby, Shrewsbury via Wolverhampton, Stratford upon Avon via Birmingham or Leamington, or Hereford via Worcester.
Just need an additional ticket from Stockport to Crewe or Stoke-on-Trent to enter the boundary of the West Midlands Day Ranger. Prices vary, depending on TOC used, route taken, maybe an extra £15-00 or so.