Another one here who is not defending the lies and misrepresentations of either side. But it is worth remembering what was said about the £4300 at the time (18 April 2016):

"Reality Check verdict: The precise figure is questionable and probably not particularly helpful. If you want to be influenced by economic modelling, the useful thing to take away is that the Treasury thinks leaving the EU would be bad for the economy, by an amount that would dwarf the savings from not having to contribute to the EU Budget."