Generally 'get back' to a habit or practise:
'go back' to a state/condition/placeCode:I must get back to playing the guitar every day.
However, often a place implies both a condition/state and a habit/practice. So usages can overlap - e.gCode:At the age of 52 he found that he had to go back to square one and learn a new job.
(If they really meant a place, you might expect 'go'. As usual, only the context can tell you which is best. )Code:They wanted TO* get back to the Garden of Eden.