I'm no good on the redundancy/move office etc part of your dilemma.
But I thought it might help to hear the perspective of another DM of an Aspergers/ADHD DC and her experience moving to independent returning home from school etc.
In the latter half of 4th class (age 10), I would go to the afterschool club to collect DD, she started putting her bag into the car and walking home herself while I drove home, (no roads to cross, but I had to drive from train and had to appear in person so that staff would allow her to leave). We talked about it at home before, and agreed that I would have to see her waiting at the pedestrian exit of school grounds as I left the driving exit (100 yards apart), I would drive to the entrance to our estate, turn off into the estate and then pull in and wait for her to get into the estate walking from the main road. Once I knew she was off the main road, I would drive the rest of the way home and she had 10 minutes from then to amble along.
We built up to afterschool allowing her to leave herself at the same time I was due off the train (I had to give written permission for that, and I would ring if there was a problem) and we'd meet at home. She was doing that by Halloween in 5th class (almost 11).
Due to a bullying problem in afterschool on the school premises (a classmate so spilled over from class), she changed to a different one that Christmas, and I had to collect from there twice a week. But part of the compromise was that she had to drop 2 days of afterschool extracurricular activities that she loved (they couldn't collect at that time) but twice a week she was allowed to come home after afterschool activities in school and do her homework/get a snack/watch tv for an hour until I got in (the 5th day she was collected by someone else from a different activity away from school and I would collect her from that house).
She had her keys, and a remote control fob for the alarm (so didn't need the code). She had a mobile phone (school policy in place for senior pupils who needed them for getting to/from school and handing them to teacher to mind all day long, with signed permission form from both parents and pupil annually). And she had strategies for what to do if approached en route, or if she had any problems once home (ringing us, going into houses she knew on the way, asking neighbours for help, and never talking to strangers etc).
In 6th class, aged 11.75 onwards, she didn't go to afterschool club at all anymore, to go to activities in school that she was missing and now goes home all 5 days most weeks herself, leaving school between 3.10 and 4pm (depending on the activity), while I get in at 6. Some weeks, someone collects her from the other offsite activity and minds her, but other weeks it is another Mum who drops her off at home when passing. And there are some days that a few of them are walking together, which she likes as a chance to chat (she's fine walking alone, but walking with the friends was not an option from afterschool).
We made sure she was able to get herself a snack - she was already doing pot noodle type snacks using boiling water at summer camps using a flask of hot water or the burco boiler there so we made sure she was comfortable with the microwave and the kettle first. And that she was happy to make herself a sandwich, or other cold stuff, or toast (as a fussy eater though, the pot noodles were the norm).
Then moved on to the grill and remembering to turn it off again after using it.
Then the gas hob.
She had always been involved in the kitchen - this was about her taking responsibility for herself there when she was alone.
We also went over what to do if something went wrong - her keys didn't work, the alarm went off, she had an accident or just a fright/lonely etc (phone numbers for DH and I, and neighbours, and emergency contacts). Neighbours also were happy to keep an eye if needed (a couple are home most days - 1 WAHM and 1 retired lady that DD knows well - we're a sociable friendly street). And also if anyone approached her while walking, or knocked while she was home alone.
Strict rules on allowing friends in while we weren't there (basically, not at all initially, and moved on to allowing 1 friend in occasionally once both had done homework and she rang me first to say it). And on going out again once she was home (so if we needed milk from the shop, she could go once she rang me to say that she was going and when she would be home again).
It was a little hard for DH and I to agree to this, but in our case, the bullying really meant that things had to change and we couldn't change our work, nor was going back to an au pair an option at this stage (we had one for 4 years when she was smaller and DH travelled a lot). But we took it in stages, and when we had to take action to deal with the bullying, it meant DD was already somewhat prepared and we could trust her. She knew that, if she didn't act properly (so didn't do her homework, let friends in when not allowed, spent all afternoon on the Xbox, left a huge mess or appliances turned on in the kitchen etc), that she would have to go to the new afterschool EVERY afternoon, so there was an incentive for her to make it work too.
If anything, it's all going to go backwards when she starts secondary this September - as sports will go on until 6pm and it's a bit further away from home, so I expect to be collecting her most evenings on my way from the train.
But it was about laying out what to do, and what the plans were, and what the plans were if something happened that wasn't expected, that made it work. She needs routine (the aspergers bit) and once she knew what to do, and how to manage if something went wrong, then she really surprised us by how well she adapted.
I know this is a bit long, but I guess I'm trying to say that your DC may surprise you with what he can cope with, if you work with him on strategies. So even if you DO have to change work around so that you cannot be there every day after school, like you can now, it is something that you may be able to work on to make it work for you and your family, if you take enough time to adapt and build up the strategies and plans with them.
We were very pleasantly surprised as well, when we got home the first month or so to the table set for dinner every day - which DD took it upon herself to do to help at home. That didn't last, but we can ask her to do jobs some days - like hang out a wash from the machine (thrown at the line but at least outdoors for drying), peel potatoes for dinner (she might get half of them done, which saves time later), or walk to the shops for bread or milk if needed.
We still checked homework when we got home, and did reading with her at that stage. But she was soooo much more relaxed than having had an afternoon of those boys in the afterschool. We make sure there are a few things in the fridge/cupboard that she can snack on and choose herself. But it is very do-able.