How do I bathroom / kitchen / extension? etc.

Not sure your relationship needs saving, that solution looks great 🤪

A curtain in front is an in-between solution but it sounds like that won't wash.

Look at something like Fittingly, I'd be very surprised if that came out at £10k based on some of the projects I've seen on here. You could save yourself a few quid if you find a way to use the drawers you currently have inside cupboards.

Just putting sliding doors in front of what you have there would be a start.

TBH I think that looks great and I am very jelly of that much space. I have two shitty victorian built in's that are not even done well.

What Airhead said basically, or custom self build. Another wild card is PAX + carpenter to make them look built in.

I’m absolutely shocked at the cost of fitted wardrobes. I had no idea.

Materials are (comparatively) cheap, but labour is currently very, very expensive because demand is high, because money has largely been criminally cheap until the last couple of quarters.

It feels like there are two separate questions perhaps; more storage doesn't have to mean a build in wardrobe.

Looking at that space, I'd certainly consider trying to put a shelf above the current rail to get more storage space.

I'd try and tease out what a built in wardrobe is going to achieve that your current solution isn't, appreciate this might be a difficult conversation in current circs.