I was thinking of maybe having a bedroom extension built.

It would be on the 1st floor and on top of an already existing flat
roof kitchen extension. I don't know if the foundations of the
kitchen extension were designed to hold the weight of an additional
floor as it was already built.

The extension would be approximately 7ft x 7ft built of blocks and
pebble dashed. The wall of the house which would have to be knocked
out to extend outwards would be (I assume) a load bearing wall as it
is an external wall).

Was just wondering if anyone would know roughly what it might cost to
build such a bedroom extension. Just a vague idea...