The vent is accessible and a ladder isn't needed. There is already a 3-inch hole, but It's not doing the job and a larger 4-6-inch one needs to be cut to accommodate the ducting.
Should be a short job and depending on the quality of the work and price there is likely to be more jobs with us in the future.
If you have a handyperson/builder you can recommend or would like to quote for the job, please get in touch.
Cutting a larger hole around a smaller hole is a lot harder than you assume. Its way easier if no hole at all.