So long as the styles relate to each other (ie the sofa is not heavy and old fashioned!) I say go for it. I love the blue chair.

Would go a classic navy and cream , with rich gold accents, like this pic but reverse the wall colour and lounge colour, and with your English lounge choice and decor, it would look refined and classy. The navy would go well with your grey/taupe carpet and the walls, and your window design would lend well to the old Victorian/English style. Just one idea to consider :)

Fabric that is anti-bacterial, durable, UV resistant and breathable is much easier to take care of than polyester fabrics, commonly found in mainstream stores. If there is anyone who suffers from skin conditions, allergies or sensitive skin should consider natural fibres like Hemp and Organic Cotton which won't irritate the skin. Read more: https://www.hempgallery.com.au/upholstery/

Tan leather sofa look great with grey. I love my leather sofa, grandkids have been jumping over mine for years and still looks great, so easy to clean. I've had the fabric sofas and they always start looking shabby after a while. You can cover them, but what's the point, nice sofa and you have to cover it, no way. Just if you get leather, condition it every 6 mths, they will tell you if you buy one, only a matter of rubbing conditioner into it gently, easy