I've just moved. So I'm the same process but in a spare bedroom, not a garden office but about the same size as you office. Most of the stuff is still what I had at my last place.

Current setup

- Desk against the wall. Window into the garden on my left to give me something to look at other than screens.

- Ikea Bekant sit/stand desk. A few years old now but it has been fine for me. I've not used the motors too often. Honestly I thought I'd use the different height more often.

- Generic gaming chair. It was around £120 years ago. Purchased because it was much cheaper than an Herman Miller and the like. It has been fine certainly better than office chair of a similar price point. Coming to the end of its life. Something I'm actively looking to replace in the next couple of months with something more high end.

- Cable trays to keep most of the cable off the floor. Triple monitors have a lot of cables. Cables on the floor just get in the way and collect dust.

- Triple 27 inch monitors on a monitor arm bolted to the desk (https://www.amazon.co.uk/gp/product/B01MR0448N/).

- Logitech Brio Webcam on a Elgato mount above the middle monitor.

- BenQ ScreenBar monitor light (https://www.benq.eu/en-uk/lamps/computer-desklamp/screenbar....) over the middle monitor. Expensive. I'd get one of the cheaper knock off if I was buying today.

- Two Elgato key lights.

- Stream Deck XL for short cuts and to control the lights.

- Mechanical keyboard.

- Gaming mouse.

- Old PC speakers I've had for a decade or more.

- Giant mouse pad.

- Laser printer/scanner. I still end up having to print stuff but not often enough to avoid inkjet drying out

- Everything that can be on wired ethernet.

Things I'm looking to change

- As mentioned. A better chair. I went with a gaming chair as it was much cheaper than a fancy chair while still being better than a cheap office chair. Originally I was working from home occasionally and could justify the cost of something a Aeron or similar. Now I'm working from home most of the time, that equation has changed.

- A better mounting system for monitors, lights, webcam etc. My current monitor mount is mostly great but the end of the outside monitors do droop a little. When I purchased the mount I only had the monitors. The lights and webcam mount were later additions. Having a single mounting solution to fix everything to would be great. Better support for ends of the monitor arms would be lovely.

- Replacing the Screenlight with something controlled from the PC/Stream deck would be great and generally being able to automate things via the Stream deck.

- Getting a dry erase board. Mostly to sketch out ideas. The big thing I've missed from an office over the last couple of years

- Book and general storage. So I can have my work related book near me when working and not cluttering up the rest of the house. The new place I finally have a door I can close on the office when not working

- Better cable management. Things are fairly clean currently but could be better. I'm thinking about cable duct on the monitor arms for the video, power, and USB cables

- Air con. All the kit kicks out some heat. This has been great over the last few weeks when it was cold outside. I expect it to be less welcome once things start to get warmer.

- Blockout blinds. The curtains I have now are just what was here when I moved in and aren't great. The office gets sun in the afternoons