My children have complex needs, EHCPs, special school places / EOTAS, multiple diagnoses at a young age, and I work supporting other SEND families mainly in my area but also nationally. One has a disability social worker and we get payments for a respite carer. One with multiple diagnoses in a special school doesn’t even get any support from SS.
I don’t think SS would come in and take your children away, however I find it unlikely that you would get any meaningful support. The disability team wouldn’t touch this case in a lot of areas (assuming your child is mainstream, no EHCP, and not displaying high levels of need outside of the home, they will likely be deemed not complex/high needs enough) so you’d probably end up with a general social worker if and it’s a big if, you got anything at all. They probably wouldn’t understand all that well and it would be meetings to attend without any of it resulting in any practical help. They could potentially be judgemental and concerned if they believe you’re not coping well in a situation where they may not see all that much need. I know people are saying that the disability SW aren’t just for severe disabilities but in reality, resources are very limited with parents of children with very severe needs often fighting for scraps. The situation you describe - while I’m sure is horrible and I’m not trying to minimise that - is very sadly now very common and a big part of why the country has seen a steep rise in home education, so they just will not realistically typically offer help in this kind of situation because the resources aren’t there for all who need help.
It certainly won’t meet the criteria for things like respite care, which is the main reason most families I come into contact with seek out SS involvement, alongside supporting complex case coordination where there are very complex health (physical or mental) and supporting with things like grants for home extensions and so on, none of which which appear to be applicable here.
You may be signposted to parenting courses, which are often useless, but there are helpful ones out there which you can seek out yourself without the hassle of SS. You may be signposted to support groups and so on. All of this signposting could be provided via local SEND groups either on social media or in person. There are charities and other organisations that offer courses on different aspects of SEND in order to help parents understand and better support their children - I’ve did various online courses myself in the early days (everything from sensory processing to SEND tribunal processes).
Really though it sounds like what you need simply isn’t really SS remit. It sounds like ADHD meds may need looking at - an additional dose can be given to help with that after school time, so do go back to the relevant prescriber - and for needs to be better met in school. And if you’re not confident in whether you’re using the right approaches there’s a whole host of different ways you could get support with that, none of which require SS. I’m not sure what SS could even do for you as it’s probably school that is the trigger. If needs are not being met in school you may need to look into an EHCP. If you really want something akin to social care then you’d probably be looking at Early Help.