I think if you know where the family lived you can physically search through the pages by county, civil parish, sub-registration district, and enumeration district.
It's not too bad if you have an unusual surname - locate them in the summary books first, make a note of the details of parish and districts, then go to the '1911 census' and enter those in the 'browse' section on the right. Then you just have to go through the results page by page.
I successfully found a couple of familiesusing this method a while ago (I hope I've explained the process correctly - as I said, it was a while ago

).
I guess you can also use the 1911 census site to get the same details and then enter them into Ancestry's 1911 census boxes ...