Hi Jean,
I subscribe to Ancestry.co.uk, and fill in the "Search UK Census Collection" or "Search a Specific UK Census by Year" using BL's index numbers the same as before. The latter choice is usually more reliable.
When they throw up that new box in front of the Search options I minimise it out of sight with the arrows at the top. Sometimes it irritatingly flashes up again while the page is loading, so minimise it again and the screen is the same as before.
What I find REALLY annoying is when I attempt to enter www.ancestry.co.uk instead of my short-cut to the censuses, and it diverts me unasked to www.ancestry.com.au because it wants me to take up that subscription as well, and I have to try several times before I can get into co.uk.
It is also irritating that so many UK records they have (like probate and parish registers) are available only on the world-wide subscription, but they don't tell you this until you try to look at something - there is nowhere on their site which spells out exactly what is available before you hand over the money.
Pity they didn't fix that Registration district: Anglesey, Sub-registration district: Holyhead for the IOM, and their index errors, rather than introducing additional graphics.
Sue