Thank you for your helpful ideas.
I had in fact been on a minute dose of dosulepin (25mg a day) for many years as a migraine prevention. I went off this totally and suddenly when I went into hospital for my hip surgery; and looking at the advice now i see that it is recommended that you should tail the dose off (a bit difficult with just 25mg! - but I guess I could have opened the capsule and ditched some of the powder therein). It may be that some of my current problems are related to suddenly stopping it - in conjunction with surgery and its assorted cocktail of drugs plus the AF episode. All too much at once. It may be that I just have to grit my teeth and weather this storm - the mornings are grim as I feel totally switched off at the main and it is a struggle to do anything at all, either mental or physical. But I dredge myself out and try and do things.
When I rang GP on Monday I had to speak to a different one as mine was away - he was quite clear that I must not go back on dosulepin, and, having looked it up, NICE is saying it should no longer be prescribed (Sept 2014) so I can understand his reaction. I am sure that is why he went for the citalopram.
I do not usually read the leaflets either - but did on this occasion specifically because the AF is a new problem and I wanted to be sure that it would be OK, as I am very nervous of a recurrence. I will try and talk to my usual GP when he is back.
Having said all this, the depressive symptoms were not there post-surgery, but appeared a few days after the AF, which feels like a greater upset to the system than the surgery.
I am sure that time will put things to rights, and I have to weather this period of ill health before getting back to my former self. I am lucky to be surrounded by good kind people and family.