GPs can now prescribe agomelatine (although not all will), but typically you have to have tried a number of different classes of antidepressant first. I agree that it's a good choice if you can get it though - it's one of only two antidepressants that have had any positive effects on me (out of a great number), and I had zero side-effects (and I'm quite prone to getting side-effects).
OP did you have any positive effects on the citalopram? If it was the side-effects that made you change then it might be worth trying escitalopram, which is very similar but generally has less side-effects. Again though it's new and expensive, and therefore less prescribed.