Employer inflexible on night shifts: ask the expert

I returned to work from maternity leave earlier this year and prior to returning to work I made a flexible working application to reduce my hours and work an agreed shift pattern. This application was refused on the grounds of pending organisational changes and I was advised to reapply for work life balance as this could be agreed on a temporary basis and reviewed once the organisation changes came in. The organisational changes happened in October and I was told unofficially by a manager that I would be expected to follow the same shift pattern as all other staff within my team which includes night shifts. Since then I have made four applications to my employer for flexible working all of which have not been dealt with properly as I have been told that each application does not match the underlying shift pattern. I have pointed out that as it is an application for flexible working it will never exactly match the shift pattern. More importantly I have explained to my employer that I would struggle to work night shifts as my husband works nights so I would not have anyone to care for my child. I am not able to find an overnight childcare provision and my parents can only help for part of the year. I have suggested that I am allowed to work fewer nights than the rest of the team which my team are happy to cover, but I have been told that I must cover all of my own nights and secondly I have suggested that I am able to share my nights with another member of staff who is currently being allowed to sit outside of the shift pattern and does not have to work nights. I have quite sternly been told not to include that person in any of my considerations in my application. I now really feel that I am being left in an impossible position between failing to follow my employer’s instructions to work nights as it would involve leaving my child at home alone with no one to care for him which I am not prepared to do. I am more than prepared to work with my employer to come to a reasonable resolution, but they do not seem interested in considering anything other than the shift pattern that I would work if I did not need flexible working. Where can I go from here?