You could go wider but it depends on what type of dining furniture would want to use and how many you will be catering for. Bench seating tucks underneath and when it is being used you aren't so worried about the other space. You could always turn it around the other way [ perpendicular to the house] so the width is less of an issue as 10 metres is a decent length deck. I think even an extra 30cm would make a difference and not doing it may cost more in regret than the materials. You could go wider in the dining area only but it is a bit hard to judge without seeing the space. Find some furniture you like online and map out a plan for yourself - use newspaper for life size modelling. Good luck

I recommend custom making a dining table using Caesarstone that complements your benchtop using our Lyn Base in a Brushed stainless steel with a navy blue velvet chair that is harmonious with the wall colour and surroundings. This table can be made to any size that suits your space see more details at https://www.mossfurniture.com.au/product/lyn-caesarstone-dining-table/

I think a small round table is a good use of the space. I have a feeling the kitchen/meals could start to feel cramped very quickly. A table with 120cm diameter will seat 4 and 5 at a squeeze. Example table Regarding bar stools, I think you need to find something that slides under the bench to keep the space as open as possible. Finding a seat at 70cm might be a tough thing. Good luck

Try the Amazon Australia site. If placemats only come in sets of 4, then purchase two sets. Love the colours in the placemats Kate has shared.