I was in the same boat as you until 2 years ago. I cleaned my cellar out and painted the walls with rubber damp paint and the floor with rubber floor paint….best thing Ive ever done!! I skip ratted a kitchen worktop and made myself a work bench. I now have room for 3 bikes, a rowing machine, freeze, dryer and all my camping gear in a 14ft by 14ft cellar with a 6ft ceiling height.