Congrats!
I'd second online shopping along with meal planning - you condense all the thinking & planning into one night.
Have a family planner where you write the meals/other stuff. I like Organised Mum but any weekly planner will do. Or set up a family google calendar etc.
I bought the annual delivery pass from Sains which means my delivery fee (when I spend over £40) is free so I am not worrying about when it is delivered - they used to charge more for certain slots.
Do as much as you can at the weekend/evenings to reduce stress.
Give jobs to the kids.
Put a check list on the wall of things that need doing.
Set washing timer to finish for when you get back, so it doesn't hang about in the machine all day.
Do a load a day and hang it out to dry (mainly indoors on the dryer).
Send presents by anyone that will giftwrap, so you don't need to wrap and send. Sadly Amazon (as they are tax dodgers and the end of the hifh st etc) seem to be the best option but Joh Lewis will put in a free gift message.
Try to plan ahead with gifts, so you can handover when you next see x even if bday is 3 weeks time as then it is 'done'.
When I forget to post a card I usually send an emergency Moonpig card directly to recipent. They despatch really quickly.
DH and I have a weekly family meeting to run through dates/things thar week. Can you do that with your kids? Finish with something fun to encourage them?
Download key shop apps so you can do a quick purchase on the go. I have bought pants and wellies (for DS) on the ebay app, tooks a couple of mins.
Have a to-do list.
If you get a lunch break use it for admin.
HTH