Internal fire door/window between kitchen/garage

[SLacKer]

Could really use some help on this.

Background
My brother in law has fallen seriously ill and it is left to me to finish the work on the new over garage extension to get final sign off. The garage is sealed from a ceiling point of view but the current door is not fire rated (it even has a cat flap).

Now the over garage extension led to an extension in garage length and the kitchen door is now inside the garage. So I need a 30 minute door no glazing required and 4 panel to match existing doors in the house. The door frame is off the garage floor by 140mm so I am good as the minimum is 100mm.

Also there is a guest cloakroom with a small opening window into the garage. Now clearly this could be bricked up and finished inside but is there a window option to replace it with (non-opening and of course obscured glass ). The rear garage doors have windows so light gets into the garage and therefore into the cloakroom. The door doesn't need glazing as the kitchen has two velux windows, a large window and French Doors at the other end and side to the garage door which lets plenty of light in.

I have a door/frame overall measurement of 2070mm x 860mm, this is the measurement of the hole in the wall not the door itself.
The window is 225mm x 70mm

What I need to know

1. I think an internal door is fine for this is that ok? The garage is dry and has properly fitted doors at both ends.
2. I want to ideally get a complete pre hung door and frameset with hinges,locks,handles, smoke seal etc. so I can just fit the frame in the hole and I am good to go. Is this the best approach here? Where is a good place to find such door sets?
3. Any packing of the frame is done using mineral wool. Is that correct?
4. How to measure and get the right size frame. Do I just find the largest dimensions under the overall dimensions above and then pack the gap?

Thanks in advance.

[bobtail4x4]

the window needs 30 mins fire resistance, unless the door from it is a fire door.

[SLacKer]

bobtail4x4 said:

the window needs 30 mins fire resistance, unless the door from it is a fire door.

The door from it is not a fire door but I could easily change it to a fire door with smoke seals would that pass building control inspection?

The garage is not used for car storage so the chance of a fire is remote but I guess the regulations are there to allow exit of the property within the 30 minutes and smoke is the real killer in fires.

[bobtail4x4]

yes you are just moving the line of fire stopping back a bit,
its not generally cars that catch fire, its the white goods and stuff.

[henrycrun]

I think the fire door has to be self-closing(?)

[bobtail4x4]

it does,