kitchen table lady
Someone who dabbles in a profession that they have little or outdated knowledge of.
Empty-nester who decides to dust off her twenty-five year old education degree and tutor local kids at her kitchen table, hence the term "kitchen table lady". Because she's a bit older people think she knows what she's doing, but since she hasn't kept up with changes in the field all of her methods are outdated. Also applies to decorators, designers, therapists etc. who may be well-intentioned, but are too backwards to do any good.