Travelling to Nigeria from the UK

Hi, I’m hoping to travel to Nigeria next year but there are no appointments at the embassy in London till February to renew my expired Nigerian passport and to get an appointment for my sons to get their first Nigerian passport but I am planning to go earlier. Also can’t get visas as the appointments are also not available till Feb. I was informed I could travel with my expired Nigerian passport and my sons can get emergency travel certificates. I wondered if anyone here has actually travelled to Nigerian with an expired Nigerian passport (having a valid British one) or ever used the emergency travel certificate? Even better does anyone know of any way to go about having a fast track appointment at the embassy to get the passports? If you’ve managed to read this essay 🙈 - thanks haha! And one last thing, any mums here been to Nigeria (Abuja) recently? Any tips?