Family Visit

[Dwayne02]

Hi all,

I am new on this platform and I will appreciate if you can all help.
I am a british citizen ( by naturalisation )
My partner is currently in Nigeria and I plan for her to visit me next February 2019.
She is a Nigerian citizen. We are engaged, have got married traditionally (plan to do the registry marriage immediately after she puts to bed, we are expecting a baby by the way)
In the next one year, she has no intention of settling here but will like to visit in February 2019 with the new baby. We will all be travelling together.
I plan to just apply for a visit visa for her for that trip, my understanding is that the our baby will be a british citizen ( due to myself being one ) hence -
-What category visa is applicable to get her to join us on the trip? We will be returning home together after the trip by the way.
- I work contracts here and I have a business back in Nigeria. What documentation will I need to provide to facilitate a smooth visa application?
- Am I better off returning to the country first, then applying for the visit visa from here?
- Am I better off applying for my child's first travel passport in Nigeria or from here?

I will appreciate your various responses as I consider my options on this matter.

Thanks