First of all, if your home country does not allow dual citizenship, then you are committing a crime by not surrendering their passport back to them. If its an automatic loss, such as Indian citizens loose their citizenship as soon as they obtain any other citizenship, then there is no going back.
There is no roll back pick and choose back and forth from ILR to Citizenship to ILR.
If you renounce your British Citizenship, then basically you will have to pack your bags and go back home.
Also keep in mind, that if your home country ever discovers you have gained another citizenship, and if your country happens to be India for example, then you might end up in prison in your home country for illegally using their passport.
regards