Suggest that you start with looking at how much long and short hanging you need, do you want shelves or drawers or both, do you want shoes racks, clothes hamper...
Then have a look at some wardrobe companies - some will give dimensions or templates to design your space. Otherwise grab some graph paper and draw out where you want hanging, drawers, shelves etc and see what fits.
The internal fit out for a wardrobe is dependent on what you need to store.

Hi annalisa86 sorry for the slow reply, I didn't see you sent me a question on this directly.

It depends on what your objective and budget is. If your home builder is willing to be flexible, an alternative to the basic white usually gives the project a lift. Sometimes that might still be a white melamine, but a nicer finish than the standard carcase white and in a thicker board like 18mm or even 25mm looks substantially higher quality than 16mm.

If you want to make the most of the space I've given quite a few suggestions on how to lay wardrobes out in the following articles.

Some clients prefer to have the wardrobe fit-out deleted from the build cost and then use a service such as mine or go directly to a wardrobe company to get something more tailored to your specific needs. This approach is likely to give better value for money, because building companies variation costs are sometimes dis-proportionately expensive. The draw back of this however, is that you probably will have to wait to get the wardrobes installed after your home has been handed over to you.

How to plan your new wardrobe like a pro

plan your wardrobe for the real world

Best of luck with your new home, feel free to get in touch anytime:)

Sally