Set up some educational activities for them for the day (pinterest is great for that, you don't need a huge amount of resources and play is a form of learning, if they're playing, they're learning and developing.).
Get together an 'oh fuck off' basket as my sister calls it. When the kid are pestering you, give them a basket/box/tesco bag full of stickers, card, pencils, loo roll tubes and give them a task i.e. make a robot, make a garden scene, make some fruit.
At the weekend or when you have time, try to make a plan of a long-term project they can do. If you pick a theme i.e. nature, get them to do maths activities involving nature (using leaves to count, counting how many birds fly past etc), tell them to write about nature or describe a park, draw nature, etc.
They don't have to do all of this with your support, maybe encourage them to use a timer and dedicate 10 minutes to each thing, get them to bring it to you to 'mark' it, draw big ticks and smiley faces and send them off again. Compromise with your time so they get to see you for something positive and then go off and work hard to impress you (but when it suits you)
There are a lot of education kids tv programmes available at the minute, plenty of horrible histories episodes on youtube and all kinds of science-y things too.
And maybe add some wine and a massive bar of chocolate to your next shop 