You could try the Earl’s Court YHA hostel – it’s £15 for a bed in a dorm (off-season you sometimes find you get a dorm to yourself). Myself and hubby stayed there when we went to the RAH concert this year and was perfectly fine. It’s only a few minutes from the Tube and a few stops along from Hammersmith.
Thank you deepwater!! I just made the reservation in the Meininger Hostel (about 15 pounds too); I was at this hostel in 2011 for the RAH concert it was ok...