I'm an east London trendy I suppose.
But like pp have said, what differentiates London from other fashion capitals is the emphasis on comfort and wearing whatever you want.
The look you speak of is pretty simple to pull off tbf, no matter what age. Balayage on hair with choppy layers/waves, defined eyebrows. You can look at brands like & other stories, all saints, ASOS or cos for inspiration - even H&M, Uniqlo, Zara and mango on the high streets. Sézane and rouje for a more elegant take on it.
Some of the newer trends are: Baggy and over sized is key. Stand out jewellery. Wide leg trousers and ankle length trousers. High waisted stuff. Though skinnies are still around, just with chunkier boots and balloon sleeve jumpers. Massive oversized coats and parkas. Jumpsuits and play suits.
I've been in London 16 years and thething that's changed the most is footwear! Trainers and comfortable boots are the norm now even in clubs and workplaces where only heels would do. And i love the emphasis on trousers now, much more of that on a night out than body con. Everything is much more casual.
But like everyone has said, wear whatever you want and as long as you're confident and comfortable you'll fit right in. With most London women it's the confidence with which they stride that makes the difference I find. No pulling at clothes or fidgeting with hair, just wear stuff you can then forget about till you're changing out of it.