We built our own home. It's a shame you can't go to the building shows, but you can (and I assume you have) bought the self-build magazines to get lots of ideas.
In your current kitchen, tack large pieces of blank paper to the walls, with easy markers nearby. Dob when you go to those places, and make notes 'drawer could be deeper'; work surface higher etc. That will help get a feel for things you like or not about your current kitchen and layout.
It is also a shame that you can't do 'experience days' but if you contact the main appliance suppliers, you can often get a discount for buying a number of appliances from them, and their advisors can talk to you on the phone or video.
I am not sure why you have decided on a 'kitchen furniture supplier' but I would recommend looking at everything for yourselves to see what you can do, or get a local craftsperson to do, so you are not locked in to one supplier.
My personal recommendations, the products we researched carefully and remain very pleased with, are:
Granite worktops that have 'imperfections' making them both more interesting and cheaper: www.cglgranitesales.com/
taps: www.hansgrohe.co.uk/kitchen/products/kitchen-taps
sinks: www.franke.com/gb/en/hs/products/kitchen-sink.html
Fittings: www.hafele.co.uk/en/
Ovens are so personal, but I remain delighted with my Miele steam combination oven, warming drawer and induction hob. We also have one of their excellent cooker hoods.
Good luck!