The landing needs to be treated as a room in itself and given its own personality. I can see that minimalist is your style so I wouldn't add stuff so much as adding detail. If you were to add a wallpaper on the window wall taking it up to the flat ceiling, this would add a lovely surprise as you come up the stairs. It is separate from the main stairs so doesn't have to follow anywhere else. I would keep some neutral tones in it but if you fancy a snippet of colour then go for it.Add a cushion in a similar palette to the chair and possible link the two with a rug. Another idea is to make a feature of the stair window. You have loads of space there and could really make a statement with the window by setting a cascade roman blind quite high above the window so the hem just sits on the top of the window frame. This will left your eye, make the window feel much bigger and give you something lovely. Again, it doesn't have to be colour, it's the detail that counts. This cascade roman is set high above the window using the wall for the stack rather than taking away the natural light. The other photo above I can't seem to move but it shows another cascade blind that shows that the pleats are the feature and you don't have to have anything too patterned to make a design feature. I hope that's helpful.

Don't overwater. Use a watering glass from amazon or elsewhere. Only refill when this is empty. Im in an east facing london flat and mine is fine.

It’s very small at the moment for a fig so I’d give it some time to do it’s own thing as it’s looking healthy. If it still doesn’t branch out in a year or so, then you can pinch out the growing tip which should encourage it to produce side shoots.

About the artwork - I like the first option more. But the detail is in the colours - how they work with your scheme in real life. About the smaller table - I like these; each would bring their own vibe to your space: https://www.westelm.co.uk/fluted-drink-table-h12173?cm_ite=652298_12871658627&gad_source=1&gclid=CjwKCAjwtNi0BhA1EiwAWZaANAZNKahLu9lSjii6glZbU7tFdNRZ1URr2LkiFs_y0-x2GZ1Af6Np7BoCKzwQAvD_BwE https://www.naken.co.uk/products/dutchbone-zion-side-table?_gl=115o8gp6_up*MQ..&gclid=CjwKCAjwtNi0BhA1EiwAWZaANFLLveSKK6Y5e0RZj1RzQIYjr2TUSfHTP20nN9F0RZy3kCnBE4t3uBoCM94QAvD_BwE https://sostrenegrene.com/en-gb/products/home/plantstand-p-85ea54?variant=509045-001&utm_source=google&utm_medium=cpc&utm_campaign=pmax&gad_source=1&gclid=CjwKCAjwtNi0BhA1EiwAWZaANHdsLFB91WTB2SW44WnJ6Pf77FbMmwH-1BDx2tcfHelS2lde1i_mARoC1voQAvD_BwE https://www.beliani.co.uk/metal-side-table-black-selwyn.html?gad_source=1&gclid=CjwKCAjwtNi0BhA1EiwAWZaANIixOFb_n9G-1Lv3CmrRZmUypANQ43_NuKM55iNWro38SM2jC0jlzRoCi9kQAvD_BwE https://kavehome.com/gb/en/p/rhet-metal-side-table-with-gold-finish-o-39-cm#productDetails They all are below 40cm wide so they should fit neatly into thet corner. Alternatively, check out this planter - https://www.johnlewis.com/nkuku-atsu-indoor-planter-stand-antique-brass/p110233741?size=dia.28cm&s_ppc=2dx_mixed_home_BAU&tmad=c&tmcampid=2&gad_source=1&gclid=CjwKCAjwtNi0BhA1EiwAWZaANBocG0LchzLebU66234MknPaTyBdBizMYeG_o0PmjskcmzPBe3wEwhoChXcQAvD_BwE&gclsrc=aw.ds