A 305 x 305 on that span was ridiculous.
There is the smaller option of a 254 x 254 which would have done, or even a 203 x 203 with a 250 x 6 plate tack-welded on top to pick up the cavity wall.
To specify a 305 x 305 for domestic loading on that span is not engineering, its just lazyness.
But...
If your house is 2-bed with a truss roof, presumably its a relatively modern terrace- or semi-detached house, right?
Truss roofs are not the easiest to convert, but it can be done. In that case, a dormer loft conversion would probably need four steel beams - one for the ridge, and three for...
If you overboard the existing ceiling, make sure its the Kingspan insulated plasterboard, not polystyrene-insulated plasterboard. The former has its own 'built-in' vapour control barrier, while polystyrene doesn't.
There will be vertical timber hangers further back, supporting the ceiling joists off the higher main roof purlins, rafters or ridge board.
There won't actually be much weight at the end each joist where they rest on the plaster, but agree not good practice!
That would not be adviseable, even if you could cut the brick without it cracking.
Suggest taking the whole brick out (+ the mortar below) and bed your padstone on new 1:3 mortar on the two bricks below. If your padstone is 140 mm high (?) fill in the gap between the top of the padstone and...
It's your call regarding the inspector, but he may well comment on it when he checks the foundation trench. Google 'NHBC Foundations: Building near Trees' which might make you think again, depending on the type of soil you have, and other factors.
@jeds - you beat me to it!
If that's the case, its not going to be a problem. The load distributes downwards as an ever-widening triangle due to the bonding of the brickwork and by the time it gets to the level of the pipe, it will be so 'spread out' as to be minimal.
If there's already plasticiser in Mastercrete, could it be that you've added too much additional plasticiser, which weakens the mortar?
If so, you seem to have included a yellow/ochre additive?
To me, it looks as though the mortar has dried out too quickly, even though you wet the bricks first; they may have been particularly thirsty.
Did you add any plasticiser? This helps retain water within the mortar so that it does not get absorbed by the brick too quickly. It also makes the...