Best way to sure up / reinforce this purlin?

[surfysmurfydurf]

Found a whole bunch of issues in our loft that I need to fix.

One side purlin looks like this:

Obviously done really badly.

Notes:
- purlin is angled into the wall.
- one side has 25mm support on the wall, the back has about 65mm

So obviously not the recommended 150mm into the wall and also not cemented in.
The house is a small terrace but is on a very busy road with lots of truck traffic shaking the ground.

Best way to structurally fix asap (I am losing sleep)?
Surveyor wasn't able to get proper access to loft space - you live you learn the hard way.

Options I am considering:
- support purlin with steel bracket chemically fixed into the wall.
- support purlin with strut fixed to the party wall and also attached to/sitting on a joist below.
- cement in the space to fill the void around the purlin end.

Thoughts?

Tips?

ie. best cement mix? size of timber?

note: I have done lots of finish carpentry but not roofs before.

 

[Cubist]

Personally I would be nervous of using anything like say chemical anchor bolts or the like as simply drilling into that brickwork may disrupt and weaken it. Over all the timbers and the brickwork look to be in good order and in your shoes I would, if I were feeling particularly nervous, simply add a vertical timber prop rising from the floor immediately below and fixed to the purlin.