We used to fit loft ladders and hatches, problems encountered where fibreglass irritation, loft hatch to small to get out of when ladder installed,had this a few times you can wriggle up the ladder but get trapped coming down, as your bum cant get over the back of the opening,make a new opening a bit bigger than it is now, front to back, ensure there is enough space above the hatch to allow ladder to swing up and over, and also to slide down, 3.4 mdf is is ideal for the drop loft flap and a special push up and drop latch holds it in place
https://www.toolstation.com/shop/Ironmongery/d170/Catches/sd2310/Loft+Hatch+Touch+Latch/p97670
Fianlly fit a low engery led lamp in loft, never use a halogen lamp they get to hot and will set the insulation alight if it ever comes into contact with the stuff.