How do I bathroom / kitchen / extension? etc.

Isn't the whole purpose of a utility room so that you don't have to worry about integrated appliances?

This all day. We just had to replace our integrated freezer. So few choices in the our size.

When my folks did their kitchen as part of the "last" works they'd do on their house, my mum opted for non-integrated everything due to the number of integrated things failing over the years. Inevitably being standard sizes when bought, there were almost always problems finding replacements.

Personally I would prioritise function over form in a utility room and not have appliances in cupboards or integrated.

I would also have the washing machine and dryer as high up as practical. If you're starting from scratch without restrictions I seems silly to spend your time bending over or crouching.

Fwiw we have a 2yo and 4yo and still average a wash a day.

Also agree/echo with

Are you making provision for an overhead drying rack?

Is the skylight really worth it for the cost and loss of cupboard space?