Another data point here from two weeks ago where a UKBA officer at T5 said that members of the same household (e.g. parent and child, or spouses) where one is a citizen of an EU country and the other is not can/should still use the EU queue.

Worst case, the desk you get to will not have an entry stamp available and you will have to wait for them to get one from a colleague. Even then you should be through much faster than if you go the non-EU route.