Make a rub out of the paprika, salt, pepper and oil just to combine.
Rub over the whole chicken with the paprika rub ensuring full coverage.
Then cut up the lemon and onion into wedges and stuff in the chickens cavity (depending on the size of the lemon and onion you may not be able to fit it all in so just fill until the cavity is full).
Then place in the slow cooker on low for 8 hours.
Notes
I like to place foil straps under my chicken to make for easier lifting once cooked.
The chicken produces lovely juices during cooking which i strain and thicken using cornflour and water for an amazing gravy!!