Thanks for your replies. I think I’ll skip it and get a smaller one.
70x120 is the size of the actual box frame that the ladder fits into (I.e the opening size) it’s a tb Davies luxfold ladder.
FYI it’s only for lightweight storage in the loft space.
My roof is a truss roof (I think) and the ceiling beams and truss that goes up to the roof are 55cm apart.
The loft ladder I've bought is 70cm wide 110cm long. Can I cut one of the beams to make it fit?
Here are a couple if pics of the loft space:
https://imgur.com/a/deF7Nsy
Or is it best to...