People saying there's been no information about this - it's only just become law. It would be a different campaign before it became law. There is no guarantee a bill will become law, even though in many cases, it does just seem a formality. Now there's a year before it goes into effect, and that’s when there should be an information campaign. (Whether that will happen, who knows with the way government currently is.)
I have carried an OD card since I got my provisional driving licence as a teen. I've given blood every time I can since I was 18. Can’t currently because of meds I'm on; suspect that were I to be run over and die tomorrow, my organs wouldn't actually be much use to anyone, either, but that would be a medical decision, not mine.
They can have any part of me except my eyes, which is reflected in the ODR. I have no rational reason for this at all. I've had my eyes lasered before, but if that would be a barrier (I assume not; I can see through them,) I have made no effort to find out. It's an entirely emotional decision. So I'm not in any position to criticise anyone else's views on donation - besides which, there are all sorts of reasons for not donating. The main thing is to have thought it through for yourself.
The most important thing is to talk about it with your families, especially whoever is NoK, while it's all theoretical rather than at a hospital bedside. It doesn't matter if it's opt in or opt out, whether you are a would-be donor or not; what is important is that your NoK know where you stand on it. My sister (my NoK) knows I carry a donor card, as I know she does. We also knew our mother's views on organ transplants, which meant that when she was in ICU and a possible treatment down the line could have been transplant, we could both confidently say she wouldn't want it. (As it was, she never recovered to a point it would have been feasible anyway.)
While you're talking about organ donation, please also make sure you have a will, particularly if you have strong views on what sort of funeral you'd like. That will also be helpful to those left behind, whether it's decades, years, months, weeks or days away.
Just talk about it together. Let each other know your wishes when you don't need to know.