It's not just cheap printers that have expensive inks. My printer isn't cheap, could be the same hp model already mentioned. Will not work with compatible or refills. But then the compatible ones are often false economy, as ironically my old printer would accept them, but was constantly replacing them.
Raspberry pi doesn't work with a lot of homework sites. They have very, very specific operating requirements.
Cheap tablets aren't that great either for homework. I have a fire, it's a tablet, great for reading books when not in the sun, great for games, silk not so great and terrible for typing essays. I also have another tablet, cost about £30 when it was released target audience was for students. Pile of rubbish. Galaxy tab mixed reviews, but the uni students I know who got them as bundles have gone back to laptops. So this brings you back to the Dell, hp and IPads couple of hundred quid and have limitations (as a school we was goi g down the tablet route. Tested tablets for over two years. Desktops and laptops replaced with desktops and laptops) then of course the higher end tablets aren't cheap and laptops suddenly become a better option.. this is of course if you have the cash.
Op might have smart phones and tablets. We don't know what they are (my ds had a £20 smart phone, great for calls and a few games). We don't know when they were purchased. Could be several years old when finances better - could be ill health, redundancy, zero hours contract households. They could have been gifts. Could have won them. Could have been a trial.. that's the thing we don't know. To say her and others in her situation should be priority is unhelpful.
Answer me this - you are a family of 4. After rent and council tax has been paid you have £100 to pay for gas, electric, food, clothing and shoes, travel to work/interviews/medical appointments/school, cleaning products, toiletries where is money to come from to buy a laptop, and to pay for internet? This people is the actual reality for some families out there.. and before the old get a job is trotted out, this is the household that is just over the cut off for fsm, or on zero hours, or unable to work because of illness.