Hey
I work full time but compressed hours over 4 long days and have one in preschool one in nursery. I'm not a single mum but my husband is not exactly a self starter on the home / parenting front so I carry the mental load and most of the practical load.
I've found outsourcing helped and opting for as much convenience as possible. It obviously costs money but I found a good and less expensive cleaner who can do our whole house and change the beds in 2 hours - it just means that i don't feel guilty about not doing a big clean if I can't manage it one week and just kind of keep on top of tidying etc. it also means the night before I do a proper whizz around of each room so everything is put away etc.
Meals are all planned and unfortunately a bit samey week to week but it means I know how quickly I can prepare them based on what else I've got on that day. A few easy slow cooker meals I can just chuck in (pre chopped veg helps!) one "easy" dinner like a pizza or something I can whack in the oven / air fryer etc. if your DD is getting her meals at nursery could you do Gousto for you on those days? When cooking make extra to freeze for a quick meal another day / have for lunch the next day.
Toys all stored in crates - makes it easy to put away quickly and stack neatly. Makes me feel on top of the house and like I have a grown up space when they are in bed.
Laundry I just have to fit in around stuff but am looking into an ironing person to take that job off my list.
Made peace with being "good enough" rather than perfect.
As for work I make my best effort at being totally focussed on work during those hours. I'm clear with people when I will need to finish for the day / no longer be contactable because I have other responsibilities- and I'm very clear about what I will commit to, for example "yes I can get that done for you, but it won't be until Tuesday as I have a lot of projects to progress before then"
Be kind to yourself - it's bloody hard, and usually thankless. We are expected to work as though we don't have children and raise our children as though we don't work.