David Oneill wrote:

However, I have been told that as I will be installing built under
fridge, freezer and dishwasher it would be better to have the units on
top of the flooring otherwise there will be a lip in front of the
appliances and make it very difficult to pull these out if they need to
be repaired or serviced.

You've been told right. If cost is a particular issue, you could
laminate for the first 10cm or so into each appliance hole, and build up
to laminate level with hardboard or similar for the rest of the depth;
but laying wall-to-wall laminate will give you more flexibility in
modifying the kitchen layout in future.

Stefek