Thank you to all who took time to give their advice here. The weekend was just pure hell quite frankly and it has made me try to take a step back and look at how we can avoid things being so bad again.
Re. Nursery, sadly completely full for this summer but am definitely going to ask to change to full time contract so that would mean he does 3 days a weeks through the holidays as well. This would allow us to give the DC more individual attention as well.
His behaviour at nursery is fine, he has the odd stand off over things like having his suncream put on but I don't think he has the tantrums on the scale he does at home or else I'm sure they would be telling us about it. So like a PP, said we know he can behave well and that tells me the triggers for his tantrums are at home.
His communication is good, really good in fact, would say he talks better than average for a 3 year old but he's still only 3 so I think the issue is his understanding on why he can't do something or indeed has to do something. I also think he plays up worse for me than DH but I'm not quite sure why that is. Due to our work routines, DH has to do routine things when I'm not at home like baths, cleaning teeth and DS doesn't usually make a fuss. However, when I do these things with him he seems to use it as a chance to test me and see if he can get out of it. Does quite often mean that I rarely seem to be able to do much with him in a calm manner and perhaps my guard is already up before we start. Brushing teeth is one of the current battles, he just will not let me do it however I try...let him do some first, sit on my lap, promise of a reward afterwards.
I don't think people are wrong to consider SEN, it has crossed my mind as he can be so volatile over the slightest thing and so completely different to how DD was. But ultimately I think he is just a challenging 3 year old. He's fiercely independent and wants a lot of control. I do try to pick my battles but comes to a point where you have to stand your ground on some things. A PP mentioned how timeout made things worse for their DC, this is definitely true of DS, it just enrages him even more. I feel like he is just really struggling with being this age.
The things that stand out from peoples posts are routine and getting out of the house. This is definitely something that has taken a slide recently. So we will work on that. I think I've become stuck in a rut of constant exhaustion and the effort of getting out and dealing with the fuck wittery of getting ready to get out of the house has led to me not bothering if I don't have to. We have a big garden so I try to kid myself he can just run about out there instead but it's not the same as going out and about. I think it's the stimulus of actually being somewhere else that satisfies him rather that just burning off energy outside.
The other thing is attention and negative energy. I think to a certain extent recently I've sort of checked out emotionally. Love the bones of him but also struggling to cope with him and my metal health is suffering. So I think my coping mechanism has started to be that I am distancing myself from everyone when I can because I feel it's better for me to not be around them if I'm in a negative mood. Maybe at times I'm not making enough time for him and this is also effecting his behaviour. But when I do give him attention, it's often constant demands which then lead to tantrums as eventually it will be something that I have to say the dreaded no word to. Another one of those vicious cycles.
It's a storm we've got to ride out I think but I think we can improve by getting some structure back to our day. Going to read the thread again as some great advice here, thank you 