I realise this topic is over 2 years old but I am in a very similar situation, again a bungalow with a block wall continuing into the loft to support a purlin.
The section of purlin has a total span of 7m (no joins) - the wall splits the space into 2 rooms (2.5m & 4.5m in length). I would like to remove the wall and replace with a new wall giving me two rooms of 3.5m in length (i.e. supporting purlin at its mid point).
I was wondering if the original poster (tombo8383) completed their project and if so what solution was chosen?
I am leaning towards going for a non-load bearing stud wall & a RSJ running above it with a post to support the purlin (this would mean no new footings required) but still not 100% sure.
Suggestions from the original poster or anyone else appreciated.