If your kids go to school then will you be paying for it, or do you expect the same sort of free public education you get from the US? If the latter, that's at least $10,000 per child, so at least $20,000.
Are you going to pay UK taxes for the year?
Who will cover your medical?
It sounds like a net-negative for the UK, from a financial sense.
It's certainly possible to move to another country as a self-employed person, but that requires showing funding, and likely a business plan, marketing plan, etc. to show it is viable. See https://www.expatica.com/uk/employment/employment-law/the-uk... .
https://www.gov.uk/healthcare-immigration-application/pay
https://improvement.nhs.uk/resources/overseas-patient-upfron...
As with anything connected to the NHS it gets a bit complex when you look under the hood: https://www.gov.uk/government/collections/nhs-visitor-and-mi...
The list of services exampt from charging are here: https://assets.publishing.service.gov.uk/government/uploads/... (It's more complex than the list I'm including here)
---begin quote---
Exempt services
The following services are free at the point of use for all patients. A charge cannot be made or recovered from any overseas visitor for:
• accident and emergency (A&E) services, this includes all A&E services provided at an NHS hospital, e.g. those provided at an accident & emergency department, walk-in centre, minor injuries unit or urgent care centre 2 . This does not include those emergency services provided after the overseas visitor has been accepted as an inpatient, or at a follow-up outpatient appointment, for which charges must be levied unless the overseas visitor is exempt from charge in their own right;
• family planning services (does not include termination of pregnancy);
• diagnosis and treatment of specified infectious diseases (listed at Chapter 4);
• diagnosis and treatment of sexually transmitted infections;
• palliative care services provided by a registered palliative care charity or a community interest company;
• services that are provided as part of the NHS111 telephone advice line;
• treatment required for a physical or mental condition caused by: - torture; - female genital mutilation; - domestic violence; or - sexual violence,
except where the overseas visitor has travelled to the UK for the purpose of seeking that treatment.
I'd give it at least a year before you decide to come here!