You can borrow wallpaper books from suppliers and compare some you like by holding the samples up to your walls. Be sure to test how well they complement each other at different times of the day under different light conditions. I know it's hard to know for absolute certain how a particular wallpaper pattern will look on a large scale, but it's a place to start. And the people at the decorator stores will be happy to advise you.

there are some interesting putty grey colours in the knots of your floorboards. I reckon it would be worth holding some paint swatches up to the boards and see if you can find one that ties in with those driftwood tones in the timber . Then order a sample pot in a half or quarter strength version of the matching colour then see how it looks. Otherwise it is so hard to go with colours people have named, as every space has different light. If you are happy with the colour of the floor boards, let them guide your choice and you can't fail (as long as not too dark). :)

first store the dead animals the out of sight and consider Antique USA (white with a grey base) for all the painted walls, plain ceiling white for the plaster ceilings, white semi gloss for all the painted architraves and skirting boards and keep the timber ceilings and timber doors but replace the floral door knobs with plain satin chrome and use simple flat white and satin chrome ceiling fixtures in all the low ceilings and simple pendants in the high ceilings (good variety of both available in major hardware stores) and it would be worthwhile to replace the patterned row of tiles with plain white ( a textured white tile if you can't match the colour) and clean the blockwork walls and the floors look good

Very light grey on all walls would be nice or white. Lighter colours like white tend to make spaces bigger and in ur case this needs to be done. The artwork on the weight bearing wall (in kitchen) needs to go as this draws ur eye to the wall . The railings on the stairs need to be painted (either colour of the walls or white)as this will help blend into the background and make the space look bigger.