A previous study by Szmrecsanyi revealed that this irregular past tense form is frequently found in the Southern regions of England; past tense done is a particularly southern feature that becomes less frequent as one progresses north (2013: 55).
46% of southern speakers either use this construction themselves, or frequently hear it in their area. Despite research from Szmrecsanyi (2013) that suggests otherwise, this figure is actually smaller than that for northern speakers (56%); this indicates that I done it is, if anything, a northern feature. However, the difference between the two regions can hardly be described as substantial.