Gentle Fawn is a soft warm grey-beige — what the trade calls a "greige" — and the single biggest mistake people make is pairing it with a cool brilliant white. Don't. A crisp blue-toned white strips the warmth straight out of it and leaves the fawn looking grey and dingy. Keep the whole envelope warm.
On woodwork and ceilings, go for a soft creamy white rather than anything stark. That little bit of yellow in the white sits beautifully against the fawn and keeps the room feeling settled rather than flat.
For a gentle, tonal scheme, Dulux Almost Pistachio (LRV 80.3) is a lovely partner — a light, soft green that reads almost neutral but lifts the fawn just enough to stop it going monotonous. It's a cracking pairing for a hallway or a north-facing room where you want light bounced around.
If you want contrast and drama, drop in a deeper accent. Paint & Paper Library Blue Blood (LRV 16.4) brings a rich, inky depth that grounds all that softness — gorgeous on a single chimney breast or alcoves. Or go fully cosy with Mylands Cigar BH.20 (LRV 11.8), a deep warm brown that picks up the earthy undertone in the fawn and wraps the room in it. Cigar on the lower half of a wall with Gentle Fawn above is a proper warm look.
The "but what about my woodwork being too yellow?" worry — it won't be, as long as you stay in the creamy-white family rather than reaching for a magnolia, which is a different beast entirely.
Dress it with natural texture: oatmeal linen, limed oak, antique brass hardware rather than chrome. That's the whole trick with a warm neutral like this — let the materials do the work and keep the colours quiet around them. Sample big, look at it morning and evening, and you'll have an easy, liveable room sorted.