I apologise to all of you in advance, but, as I thought that if I ignored the tax return it would go away, I haven’t read all of this thread. 
So my main question may have been answered but it is this. In previous years as I worked through the online declaration, there came a point with a blank panel inviting any explanations of things not apparently covered. So where is it this year, no sign anywhere?
Just over a week or so ago I buckled down with the back of an envelope and listed all my income, Fran’s income and then added up all the transfers I made from UK to France during the year. By dividing the euros by the pounds I came up with a precise exchange rate (I know some people decry this method but it has been accepted by the Impots for at least the last 7 years without question) and arrived at 3 totals in Euros to declare.
Confirmed the, (unchanged) 2 bank accounts and signed the declaration. All well and good, but nowhere to fill in the bit I wanted to. Our UK bank is Yorkshire Bank and over the last year or so it has been gradually morphing itself into Virgin Money, and, horror of horrors it started to pay (miniscule) interest on the current account. No idea where to put this €14 so I was intending to describe it in the missing panel. So where is it, where do I declare it, or is it too small to worry about?
Another thing, I was advised last year that I should put Fran’s local government pension in a different box, and did so. This year when I did that it led me down another path altogether so I went back and changed it to the way I did it before. Made no difference before the change, nor after, so hoping for the same this year. BTW all these amounts are small enough never to have attracted tax, and the prediction this year is for the same.