I know a lot of people have said about trying to keep it light, but actually a darker feature wall (warm rich grey paint if you can't afford wallpaper or want to keep it simple), along with a bunch of mirrors behind that sofa would bring it to life. Having had small victorian homes with dark rooms and tried to keep everything pale, I realised that sometimes there is no point in fighting it! The yellow sofa (which I love - where did u get it from??) will really pop against a darker wall. Otherwise for wallpaper - there are a few websites online that you can buy from in price order and by colour. I've also been looking and you might find a pale background with some striking pattern (darker) pattern would really stand out (rather than going as pale as your curtains)

Hi. there looks to be 4 sets of pendant lights and the ŵall lights are going on the wallpaper ŵall? If so I might do away with this pendant and maybe think about downlights if needed as I think I can see a couple already. Also use table lamps as said before and use a rug to zone this area. If there's room you could also add a console behind the table

Since you asked for honest opinions, I think that is the most awful sofa I have seen. You made a great decision to cancel your order. You may benefit from the help of a professional decorator to help you with this room.

I like sofa.com had a big love seat chair from them for years. Also ordered at time of purchase a spare set of cover which is not cheap but worth it. Loaf do some great sofas.