I know these shows are remembered as "squeaky-clean" family sitcoms and it seems The Partridge Family is well-remembered in the UK - I have heard it was shown by the BBC and of course the songs from the show were popular over here.
I don't think The Brady Bunch is as well-known over here, though. I know it was shown on ITV, but wasn't it only shown in the London region?
Sky One re-ran The Brady Bunch in the early 90s but I don't think The Partridge Family has been re-shown for decades. When I saw The Brady Bunch on YouTube, it seems very dated and the jokes have also dated.