If you search DIY banquette on Pintrest you’ll see instructions and measurements. Most are in inches but you can convert them. Could you measure the seat height of the chairs you are using with the table (you need the table first) subtract the cushion height and that will give you the bench height. It does depend on the height and weight of those that will be using it the most, to get the best fit.

what happened to the old column? i think you need to add a corner cabinet (900 on the stove wall and 1050 on the sink wall) with doors hinged across the corner provides 300 + 450 wide doors and better access to the corner for storage of big appliances and to allow more space for the drawers to open, the 1000 fridge space allows an air gap and two 750 wide drawers next to the 900 wide stove, i've kept the 1200 gap between benches and island and added a cabinet (opening toward the sink allows for a 600 wide 450 deep space for a bin) then two 750 wide drawers and the built in microwave making a longer island and extra drawers next to the dishwasher ...in my experience, if you're having custom made cabinets you only need to specify the size of appliances and sink, the general layout of the room and your preferred arrangements and approximate sizes and the cabinet maker should measure the site and custom make the cabinets to suit the space with minor alteration to allow for any obstacles eg like making the pantry cabinets narrower to allow for architraves around the entry door..and it's more comfortable to walk around if the pantry doesn't overlap the architrave or encroach on the doorway

keep in mind that my plan has single external walls and all the inside and outside walls are 10cm thick to make drawing easier and the depth of the verandahs includes the eaves, adding a brick veneer would use more space and given the choice it would be lovely to plan for a covered walkway and raked ceilings in the living areas and this is a very basic gable roof but there are lots of more exciting/expensive roof options to consider

2500 x 900 or the 1000. Aim for 1100 - 1200 between benches.