I also work as a care assistant and am having the same problem, i dont want to work split shifts anymore but i still want to stay in the care environment. been looking on the nhs jobs website theres some good jobs on there sometimes but you'll need the qualifications or experience again.
You could go part time in a nursing home, some of the larger companies are more flexible with the hours. where I work you can do 16hours and baisically fit it all in where you want. Then you could and ask to do your nvqs.