[Closed] Log burner / HETAS installers....Vented fireplates - when to use them??

As abvoe really.
We're having the 'top half' of our chimney stack removed, so that it will be 'non existant in our new loft conversion. As such, at 'floor level' on the (new) second floor will be the 'end' of the chimney stack, so will have a 'stack support' converting from flexi liner to twin wall flue.
THis twin wall flue will head vertically up, and out of the (newly created) flat roof, with flashings etc etc.
As is passes through the loft conversion, it'll be boxed in (kind of within a stud wall - to distance regs of course).

I'm not 100% sure if we'll need vented firestop plates in this install. On 'ground level' will be the stack support, and at top level it'll pass through the roof.

I was panning on having a top and bottom room vent in the 'boxed in' section, so as to share some heat from the pipe with the room it's in.

In this setup (that i've badly explained) would I need a firestop plate at all??

Ta!!

DrP