What sort of floor is upstairs, carpet over floor, floor boards, etc... Underlay may work to a degree but it depends on how well you want the sound reduced. I can't see it being an acceptable solution as the thump will still resonate. Insulation between floors could work better when teamed with the underlay but would probably be invasive and you'd still have the thump's resonate.

Houzz please remove this.

This is great! Thanks for sharing

I love those benches I have used one as sewing/desk with trestle legs, love it. The following is my idea with timber bench tops and using your cabinets, This would work if you could run the plumbing across to the left,either inside or externally. ,I have moved the sink to allow you to use the 80cm cabinet as your dish rack, the window won;t allow this. Or you could just swap the sink and cooker and use other shelving for the dish rack Back wall R-L 60cm cabinet,cooker,60cm cabinet 800 void for sink,60cm cabinet.fridge. Wall, using the 80cm x 42cm as plate drainer with timber open shelves on both sides, extraction is a simple ceiling extractor fan. I have added a narrow 60cm Island which uses both 40cm at both ends,like the sink there's a void which can have a couple of stools andr rubbish binscan be placed under the sink cheers