This time last year, we had a combi-boiler fitted, which made
redundant the hot water cylinder. The previous owner had
decommissioned the hot-air heating system some time before. What
was the hot-air cupboard sticks out into the main bedroom, and the
cylinder cupboard is too deep and sticks out into the hall. I'd
like to knock down part of each of those cupboards to make them a
bit more like alcoves in the rooms.

The walls throughout the flat are concrete blocks, 10cm thick. The
section I want to remove from the bedroom is 35cm long - the rest
of the cupboard was formed from asbestos-backed plywood and has
already been removed. The section to remove from the hallway is
more complicated - it's a wall about 60cm long, and a doorway which
completes the cupboard (the section above the door is also block).

We're on the ground floor, there's only one other flat above us and
that has the same floorplan as us currently. Our ceiling/their
floor is concrete.

I'm assuming these small sections of wall are not load bearing, but
is this right? All the DIY guides I have seen talk about floor
joists above, but of course there aren't any! How do I check in
this situation? I've knocked out a sample hole about the size of a
housebrick, which shows the metalwork in the reinforced concrete
above, but what might I be looking for? Some photos of the
cupboard and hole are online at
http://www.wolfson.ox.ac.uk/~sjg/wall/

Finally, to do a neat job, I think I need to cut a vertical line
through the blocks before I knock them out of the wall. Does this
make sense, should I be hiring something to do this (if so, what)
or should I just drill lots with my SDS drill?

Many thanks as ever to all who contribute to this excellent group,
and sorry I'm so longwinded in my questions!
--
Selah