I think it depends on what age your children are, OP. Older children aged 11-14 seem to have benefited best from lockdown and online schooling: they're old enough to have heard and seen news reports and adult conversations about Covid 19 and want to be safe. Young children aged 4 to 10 may find prolonged isolation at home unsettling, surreal and claustrophobic. Unlike an adult or older kids, they have had fewer years of living to be reassured that things can go back to a safe normal.
You're probably going to be bmnbarded by a lot of trolls and self anointed "virologists" here who claim to be experts on Covid and say you're overreacting. And yet Britain has had 30-something to 40-something mothers die of Covid and 12 to 16 year olds dropping dead from it. Nobody gets magical immunity from Covid just because they're under 50. Or because they're in a school uniform. Regardless of what politicians and scientists assigned by politicians proclaim, there's no denying the fact that over 40,000 have died from it and all public health physicians agree it that Covid has increased the number of deaths that normally occur in March to July in any given year apart from WW2 many times over. And ITU consultants have warned that if case numbers rise again, the government has simply not provided enough staff, ITU wards, ITU equipment or PPE to treat huge numbers of patients. Forget clapping, rainbows or "protecting the NHS" - the government has simply not done enough to provide for the population should case numbers rise and that has partly caused the huge death toll.
The school gates do not confer magical immunity from Covid to any adult or child just because they step through them. Interestingly, a mental health study done by psychologists recently has revealed that many teens and other pupils have seen their anxiety levels go down in lockdown- possibly because many no longer have to face bullies or stresses of various kinds (eg tests, projects, sports matches, etc) from a hectic school timetable, and perhaps may have had a supportive group of teachers during lockdown who have been accessible by email where they were previously difficult to make time to speak to.
A chat I had with various parents during lockdown found us invariably discussing when the "best" or "worst" time to go into lockdown was. Eg we all agreed we were relieved not to be in a GCSE or A Level year; some said they would not have liked to be doing entrance exams this year, others said their kids had been relieved to be at home so as not to have to go into lessons with disruptive classmates and instead enjoyed being able to read and learn in peace and quiet, supported by an understanding teacher. It really depends on what year your kids are in, OP.
With regard health concerns for yourself and your children, it may be worth making a phone appointment with your GP (or hospital consultant/s if you or your DC are under hospital review) to find out what ways you could be taking precautions to minimise infection. Unless your school has a complete ban on masks, it is definitely worth discussing this with your DCs' teachers about letting your children go in with masks. Germany, Taiwan, Hong Kong and other nations where children and teachers (and bus drivers, parents, canteen staff etc) returned to school or work all wearing masks have had great success in keeping infection rates and death rates down. Viruses want a host - it doesn't care about our "bravery" or our politics. If you don't offer yourself up as a surface for the virus to attach to, the virus won't spread to you easily.
Nobody here can tell you what the right or wrong decision is. If your DCs have lovely classes of friends and sensible, supportive teachers and a headteacher who is supportive and committed to safety, there are obvious pluses of the children returning to school. But being without a school building for a year isn't going to turn your children into illiterate oafs for life either- children in the Australian outback have had distance schooling for generations and cope- even attain great academic success. Many children with chronic illness are homeschooled and also do well: I have met several whose intellectual capacity and academic attainment were truly impressive despite having to have major surgery or hospitalisation 2-3 times every year. But if you do wish to keep them off for longer, consider a proper homeschooling program and deregister so that you get more support from the homeschooling materials and organisations. Also schools will not be able to offer regular online teaching or support like they did during March to July once the school year starts in September. . Best of luck in what you decide, but do speak to your doctor and your DCs' teachers for support.