Sometimes our centre has 'play up' days. That is where the children who are almost old enough to go to the next room spend the day in there thus leaving a vacancy in the younger room.

They did it once to help me out when I was sick and DH was away and I needed to put DS in for an extra day so I could rest. Of course it depends on whether there is room in the older kids room.

Might be a good temporary solution and help you out in the short term.