The confection is known at least since 1857 in the USA (OED), but only appears in Britain in the 1920's, with the 'Cinder' and 'Honeycomb' names appearing more-or-less simultaneously.
The Sunderland Daily Echo and Shipping Gazette' for Saturday 28 July 1951 (p2) says that "Cinder toffee [is] said to come from Prudhoe", and it does seem to be the case that most early receipts are from North Eastern England or Southern Scotland.

Crunche Bar, 2015
The chocolate-coated 'Crunchie Bar' was launched in 1929 by J. S. Fry & Sons, later merged with Cadbury.
Original Receipt from the 'Southern Reporter' - Thursday 19 February 1925Honeycomb Toffee.- In a large saucepan put half pint of water, one pound of granulated sugar, and half pound of glucose, weigh the glucose on very wet paper. Boil to pale straw colour, then stir in one ounce of bicarbonate of soda, free lumps. Thickly butter a dish with a deep centre, and foot long, and hold the saucepan over it to catch the overflow when stirring in the soda. Turn the toffee on to the dish to harden.

Cinder, or honecomb, toffee
Image: 'Londonsista'