There's loads you can do to help yourself:
You deducting an hour every day for travel is child free time. For phonecalls, for quiet time, audiobooks, the radio or listening to a podcast, should you desire. If I have to travel out for work, I make tonnes of calls in the car. Work, personal and social. Do you use that time productively?
Because you choose to do things in the 30hrs your children aren't there, doesn't negate that you are choosing to fill 30hrs of leisure time with daily tasks, 99% of which could be done at other times. Plus volunteering activities you like doing.
Question: When do you think the multiple other SEN mothers who work, who have commented explaining this to you, "put a wash on?" .Are you suggesting your one SEN child prevents you from doing this when they are in the home? Every household task you have mentioned taking up your free time, and it is free time, not "free time", is stuff that the other SEN parents do with their children in the same building. Do you think that your child is so challenging that all SEN parents do all this outside school hours must have really easy children?
You have 30hrs free time during the day, plus all the time out of school. It's like me taking an hour off in the middle of each day and having a bath. Do you see it would be pretty ridiculous for me to tell people I absolutely don't have an hour's free time every day, because I choose to spend that time bathing.
What I'm getting is an hour free time. What I'm then trying to tell people is "I have no free time, I bathe in that hour."
The online shop, is another evening job. So is setting out clothes for the morning. You only do them during the day because you've got hours upon hours of free time to yourself.
Since September I've had two suspensions. Three bouts of illness. Multiple SENCO meets. The under assessment child has a new ISP to go through and another letter I need to get to his doctor. All 3 of my DC are still up, joy. Hence I'm sat up now, as they each take turn to wander downstairs. But it's a weekend tomorrow, so hey ho, pick my battles. These examples aren't to knee jerk a silly defense and "have a medal" how about step back, oh, someone with very similar life demands, yet 30hrs less than me, is seemingly coping. They're nothing extraordinary. I'm nothing extraordinary. So hang on, why is there such disparity?
At the moment you have no acceptance that nearly everything you fill your day with is a standard task you can do with DC around. You just do none of these with DC around so have engrained in yourself that you can't. If most can, including those with more difficult circumstances, then at some point you must be able to reflect that you aren't that extraordinary that you can't.
This is all about time management. A PP said, because you've got that amount of time, you've grown to make it take that long. I've got 2 bedwetters too. Firstly, puppy pads, if you don't know what I mean, Google them, very helpful under sheets as an extra layer if you've got expensive mattresses. Secondly you spend an hour a week on one set of bed changes. Longer sometimes if you're going it twice. There's only 4 of you. And 3 of those are kid beds. That's forever. Because you've gotten used to forever to do it.
For me? As I'm getting DC up, if pjs are wet, I hoik the bedding off there and then with their PJ's. Also one cabin bed and two bunk. It's one minute max. Carry it downstairs and chuck in machine. Make breakfast then switch on waking machine as they eat. Twenty seconds to leave the dining room and do that. When I get home, yank out of machine, into tumble. Bedtime, DC come up with me and sit on the floor with a toy while I make the bed. 5 mins per bed. Probably fighting over said toy.
Again, without "oooh get you" why not see this is very normal, very achievable, and exactly what you could do. More importantly zero of the hours during the school day used to do it. And yes, my DC are winding each other up as well, not grinning like the Von Trapps.
I actually had a day off today. I've polished all the stone in the kitchen. Been to the butchers. Had a pootle around a few shops. Popped to see an elderly relative. All leisure time. Then, since DC have been home, I've done 3 loads of washing, filled out some school forms, done tea, placed an online order for the weekend, renewed the car insurance, emailed the aerial man... alongside the parenting. Which tonight, no, wasn't a walk in the park. Hence still I'm up and on social media at midnight.
If you did your chores when every one else does them, you'd soon see what an inordinate amount of time you have to yourself each day. Seriously, do it, because you're wasting away your free time predominantly on little evening jobs.