New Loft Hatch

[stu4199]

Hello,
I have a Bryant home, built in 2000. The access panel to the loft is a 'push up' moulded plastic type. I have been looking for a new 'drop down' panel so that I can fit a ladder.
Unfortunately the hatch is not a standard size. It is 710mm x 565mm and I cannot find one anywhere.
Does anyone know where I acn get a new hatch of this size?

Cheers