Removing brickwork in extended bedroom from outer leaf wall

[Flinto]

Hi

Just after some advice really

Just moved house, which was extended around 1980 to add an extra bedroom, with a dormer room over the garage.

The best way to place the bed doesn't allow much room to walk around the foot of it.

I had an idea to remove a little bit of brickwork on the outer leaf of the original outer wall which is double brick plus 2 inch (uninsulated) cavity, to create a bit of a reverse alcove to about half the height of the wall, to give an extra 6 inchs of floor space for the head of the bed to sit in, thus creating more space to walk around the foot of the bed

Obviously the wall above will need supporting

Question is

Is it a good idea?
Will it look ok?
Would building regs be required?
Is it a DIY job or would I need a builder?

Many thanks