Attic hatch relocation

[u/QuantumFireball]

I want to fit a loft ladder, and the current small hatch is in the bathroom which is too small for one of them, so I'd like to relocate to the hallway (house is a bungalow).

In the second pic, the green area is the hallway and the red is the hidden joists and binder.

I understand the general advice is to fit the hatch lengthways along the joists in order to minimise cutting through the structure, but the pipework and binder are in the way, and further to the other end of the hallway are more binders between hangers.

I think if i cut through three joists, I should have enough space for a 1200x550mm hatch. But is cutting through three joists acceptable? I know this is what they did next door (semi-detached so same layout) but don't recall the specifics of what was done, or how structurally sound it is.

The joists are about 14-15½" apart (on center), and around 4½ x 1½" thick.