We used Plantation Shutters who were very good and I’d recommend (https://www.plantation-shutters.co.uk/
). We went for full height white, wooden ones (like the picture on the website under ‘shutters’ > shutter styles > full height in the menu). These were recommended as the best type for larger bay windows to let more light in. We’ve been really pleased with them and haven’t noticed the rooms feeling darker. They come round for an initial discussion so you could just chat through options in the first instance with no commitment I’m sure.
Good luck with it all!