Looking for book, probably from 60's or 70's

Hello, looking for a book that I read back around 1982 - here's what I remember:

- Written sometime before 1982 - probably 60's or 70's
- Believed to take place in England
- First chapter has "Winston Churchill" watching 2 fighter jets out of window
- Takes place like 10,000 years after some disaster destroys everyone - nuclear or biological disaster - Some human embryos were "frozen" until environment safe for humans again
- All other "people" are not human, they're cyborgs or robots, computer generated world
- Purpose of the "adults" is to make sure the human children grow up

I'd really like to read this book again, but am not having any luck finding it. Any suggestions would be greatly appreciated!