My great gran was Emma Elizabeth Hizzard (born 1878 in Canterbury). Like you I have found the name previously spelt as Izzard (Emma was baptised as an Izzard not a Hizzard) and on one occasion as Izard.
Where did Jane come from? I have no Janes in my Hizzard family at the moment but would be very interested to hear about your research. Do you know anything about the origin of the surname?
Best Wishes
Matthew