I'm self employed and do have a room in my house as an office. Before covid I worked OOH for 2-3 days and WFH for 2-3 days and now it's 5 days a week, sometimes 6 or 7 depending on workload.
One downside is the lack of exercise. Don't underestimate how all the little bits of walking from car to clients office add up or popping out at lunchtime if in a town.
If DD was home then she stayed in her bedroom or was out playing with friends, she wasn't allowed to watch tv in the living room while I was working in the office. You can't work in a shared space with kids around, it just doesn't work.
My hours vary, but generally 9-6, sometimes a bit later, but when I leave the office I switch off. I don't answer client messages , I don't check my emails. I dont look at my phone at all in the evening.
You need to set boundries on yourself and stop checking emails at night. Everything can wait until the morning. Nobody is making you do it.
Have a lunch break unless you work through and finish early. You are legally entitled to a lunchbreak so why would you feel guilty? I eat at my desk but I do stop and look at the news and mumsnet and facebook etc.
Real upsides are the lack of commute, being able to do household stuff around work, so I usually sort the dishwasher while making a coffee, I put a load of laundry on before work and chuck it in the dryer at lunchtime.
I can stop work at 6 and be in my living room seconds later.