Just to echo what other people are saying. With younger children in particular so much learning can be done away from paper and pencils! Without knowing each family's circumstances, schools are trying to meet the needs of as many people as they can. Worksheets might be what they have sent but it doesn't end there!!
Stories - where they read to you, you read to them, listen to them (audible has free childrens books online at the mo), watch films, talk about the stories - it won't seem like work but it is invaluable. I liked this character because... who did you like?... etc etc. You could get small objects in a bag that they pick out a fewtime and use them to tell a story (like story cubes but without buying something new).
Problem solving activities - can them make a den etc, junk modling, building from lego. Get a washing up bowl and they can find out what materials float / sink, what materials are waterproof and best to make an umbrella out of ... can they predict this? If you google there are lots of science activities that you can do at home that are quick and easy.
Maths can be brought into everything - counting how many (jumps, hops etc) they do, who did more? how many more? what time is it? we will do this in 10 minutes, I need you to remind me - what time will it be then? Even snakes and ladders counts as maths at this age.
Orchard games are great if you have any of them, or can get them online (I say great, I mean educational... they can be soooo tedious when you are an adult but children seem to like them!)
Those days you need some time to yourself, there are plenty of educational apps and online games - Ladybird did some good phonics ones, and Squeebles have some good maths ones.
Cooking, getting them to help pair socks etc. help in the garden... it's all learning at this age.
Every reception class will have a role play areas and 'small world' (cars and figures) for imaginative play - let them lead and use what you have -e.g. an empty kitchen roll = telescope for an astronomer or pirate, a witches broom, a megaphone, a conductor's baton.
I spy games will help phonics - you can use 'ends with' 'contains the sound...' etc.
The main thing is that they don't stop learning all together - but they don't have to be working and it doesn't really matter about the school stuff!