I agree with all of the above regarding fitters, I’m sure they can save a lot of hassle. Another option however is you could always consider doing it yourself. I fitted our carcasses and got the fabricator of our worktop to fit the work surface. Given you can have the sink built in it made everything look pretty streamlined and neat, and means I don’t need to clean around the outside edge of the sink anymore - I hated that job!
We also decided to take out the kitchen island and the wall units. I realised I can never get the bits at the back of our wall cupboards, as I can’t be bothered to get a chair to stand on. The island was huge, took up half the kitchen, and just got in the way. The space feels a lot calmer now.
A metal worksurface is great, really nice to be able to put down a hot pan and not have to worry about it marking the wood. Copper does start out upsettingly bright though! It soon ends up fading like a neglected penny. It’s cool to see the copper flash bright again if you spill lemon or tomato whilst cooking. Here’s what it looked like a week or so after going in, but it soon calmed down.
One other thing that seems like an idiotic purchase but might be one of my favourite things in the kitchen aside from my espresso machine is an instant-boiling water tap. It was ridiculously expensive but I’d get another one tomorrow if it broke no questions asked. It’s brilliant being able to have immediate tea and a pot full of boiling pasta water in seconds. We got one from Quooker. It’s ace.
I’m not sure what you’re considering for a hob but as someone who enjoys cooking I’m surprised at how much I like my induction. I had a gas hob previously and was worried the induction would be annoying. Having used a few I would say most of the joy/irritation comes down to how they are controlled. If you can try them out or know a mate who has one similar to whatever you’re considering it’s worth trying them out before buying one.
One thing I wished I’d done differently is to have the hob countersunk rather than surface mounted. Countersunk means the glass top should be level with the kitchen counter. It looks much more streamlined and avoids gunk getting stuck around the edge of the hob.