Deep clean/declutter will make it easier to keep on top of stuff when you're working full time. Prioritise which rooms need most focus as you may not get the whole house done alongside other things in a week. Any rooms you don't get done, you can declutter/clean one bit at a time when you have time.
I'd do the dirty work in the morning/early afternoon then shower and meet friends for coffee as a reward before the school run!
Good to batch cook some dinners, also spend time planning for meals once they've run out eg more batch cook ideas so you don't end up eating the same things all the time; very quick after work cook ideas like carbonara, wraps, stir fries; store cupboard ideas for when you've run out of fresh meals (tuna pesto pasta for example). You'll get lots of help from MN if you ask for specific suggestions . Make sure your store cupboard is well stocked.
Christmas: if you don't already have this, spend time planning everything you will need for Christmas. Whether you capture it in a notebook, a spreadsheet or an app, you will be able to adapt it for years to come. Make lists of what you need to buy/tick off anything you've already got. Things like candles, serviettes, table cloth, crackers, wrapping paper, ribbon, sellotape , Christmas cards, stamps etc can all be bought well ahead, often as part of your regular supermarket shop.
Another thing would be to check that you have enough work clothes for full time and that the children have enough spare uniform so that you aren't stressing if you have a busy weekend and are struggling to get the washing done.
If you drive to work, fill up with petrol, one less job in what will be a busy first week and every little bit of time adds up!
Please pencil in some time that week to chill and make yourself feel ready - hair; nails; clothes plan. And just chilling a bit!
Good luck x