TheScullster wrote:
By bricking up, I meant reinstating the brick/block work around the beam
end, particularly to give restraint to the top flange of the beam. This
would I expect make the use of resin anchors or other fixings unnecessary.

Sounds fair. You'd probably only need worry about lateral movement,
it's not going to go up/down

Does the beam go in level? Any angle would exert a force on the
extension wall that you'd need to take into account. Also, if you're
sticking it on the inner wall make sure you don't accidentally bridge
the cavity.

What measures did you take for fire protection?
Is there some paint that can be applied?

In my case the beam was load bearing so I needed 1 hour protection
which I did by cladding with British Gypsum Fireline board. In your
case, since it's not structural, and as the roof joists would will go
long before the beam does anyway, you probably don't need to worry. I
only mentioned it as it's one of the things I forgot initailly and is
worth checking.