My younger son hurt me inadvertently pretty often when he was little. (He's 18 now and has outgrown what I'm going to describe, to a great extent.)
Also he was constantly hurting himself, for example he couldn't just walk to the refrigerator, he had to get a running start, then slide into home base, but he would ALWAYS miscalculate and end with a crash. Sometimes when he was pretty small, when we were playing (it could be any activity!), and he'd make a sudden movement and crash his forehead into mine. So I can related to what you've described.
At some point the pediatrician suggested occupational therapy, to work on sensory regulation.
The OT we ended up with wasn't a great match and after a while we put it on pause -- which was a graceful way to bow out.
But sometimes an OT can provide helpful sensory regulation treatment.
I do think it can be worthwhile to get a good sensory evaluation, if for no other reason than to increase one's awareness of the child's particular sensory profile (it can be kind of complicated), and how the child's profile fits or doesn't fit with those of family members).
Also, if you suspect ADHD, ADD, or combined type, it might be helpful to get an evaluation. I was hesitant for some years, but in retrospect when I stopped worrying about labeling in school, and got some evaluations and diagnoses, I came to understand my kid better, and get better in sync with him.
If you're hesitating to have him evaluated for ADHD/ADD in school, keep in mind that the pediatrician can do the evaluation, and if he comes out positive for ADHD, for example, you get to choose whether (or when) to reveal the diagnosis to the school. Also, I want to point out that many parents think that an ADHD diagnosis automatically leads to medication. Not true. You and your child's doctor get to decide about that.
One thing that helped my son a LOT with sensory regulation was to have plenty of physical activity every day that he enjoyed. When he was a toddler or a pre-schooler, if the weather was atrocious, one of us would take him to Walmart for exercise! Sometimes we'd let him ride a bicycle with training wheels around the store (parent in close proximity). Also we learned to avoid a lot of stimulation before bed, and to keep to a regular sleep schedule as much as possible. I noticed that my son always needed more sleep than his peers. We had to make sure there were no roughhousing games in the hour before turning out the light, and keep to the schedule. Also, another rule my spouse and I worked out was, DO NOT draw a line in the sand at bedtime. The goal became, let the kid say whatever outrageous thing he might -- BUT DON'T ARGUE WITH HIM AT BEDTIME. As they say, "tomorrow is another day." Better to do the problem solving well before bedtime.
Another thing that helped was to work out an agreement with the school that there would be NO elimination or reduction of recess time as a consequence for behavior problems and/or incomplete academic work. This can be set up as an accommodation (in a 504 plan or an IEP -- if you're in the US). I think in the UK it's called an adjustment maybe. Having this as a recommendation in writing from the pediatrician can be helpful in getting it set up.
In middle school, when most students were going to PE every other day, our kid was going every day. That was quite helpful to get through the day.
Thinking about your 7yo daughter: I remember that the PE teacher explained to me some of the games the kindergartners played:
Game #1: hold out your arms straight out to the sides and imagine you're an airplane. The children run around the room in random, variable directions in a roomy gym. The goal is not to bump into anyone. The teacher explained that this game helps with the child's awareness of his own bubble and the bubbles around the other children. The teacher didn't do much explaining with the kindergartners. The children improved just by doing.
Game #2: right before going back to the classroom, the PE teacher had them play Pretend Sleep. The teacher would walk around the room gently touching anyone who was having trouble winding down. The teacher explained to me that the children needed to wind down, calm down, after so much stimulation in PE class, before heading back to the classroom.
I wonder if these two games would be particularly helpful for your son.
My son's classroom teachers tended to increase his distance from his neighbors, to prevent accidental harm to others, reduce distractions (in both directions), and to reduce over-excitedness (too much stimulation). That helped.
Could you work with your daughter to help her learn to gauge how much distance to keep between her and her brother?
If it becomes an issue at school, maybe having an extra adult in your son's vicinity (perhaps through special education) would help. But watch out, sometimes the paraprofessional (extra adult in the room) will set himself up as a behavior cop, and when that happened with my son, it was completely counter-productive.
If there are problems at home, for example when you're on the phone or cooking dinner, it might be helpful to have a Mother's Helper come over to prevent accidents. Or you might have them take turns talking to grandma on the phone. Your children might need more supervision than most, to avoid someone getting hurt.
My other two ideas to offer for your consideration are: 1 - it can be helpful for a child to be trained in winding down getting ready for bed, for example snuggle and read with a parent. If you're going to read two books, the exciting book comes first, finishing with the calming book. 2 - help the child build self-esteem by building skills in something the child enjoys and gradually gets good at. For my child, music lessons and supervised practice was very centering. He really enjoyed it and even when he felt like the bad boy at school, he could still be proud of his musical skills. It doesn't have to be music -- there are other abilities a child can develop over time.
No two children are exactly alike. For all these ideas I've shared, please sift through and see if any of them might fit.
