Back in April, when this question was last asked, Suzy64 stated that the shop is on New Street and opens on alternate weeks, between 10.00am and 1.00pm on Friday and from 9.00am to 1.00pm. on Saturday. If that information still holds true, the shop should next be open on Friday 18 and Saturday 19 August.
I haven't been since lol, but friends have and yes still seems to be at 2 weekly intervals and still just as manic and still just as fab, New st Hinckley, easy to find if you know the area and well worth the trip :o)