Hehe - Finding snakes is the easy part - getting a good macro without being bitten is the hard part - I've even got pictures from the Island of Sardinia (which they claim is snake free!). Sorry another Fuji F30 shot so I promise I won’t post anymore but it’s Pete’s fault for asking about adders;
When I was a kid I used to breed slow worms, grass snakes and twice I bred adders. Yes all found in London! First attempt was a mess as I didn't know the mothers ate their own babies but then there after was quite successful and released lots into the wild

You should see the adders mating dance – quite something!
So anyway to the question – finding adders can be quite easy actually. Firstly it’s good to note you rarely see them from Oct – March as they semi hibernate. Temp below 10 degrees and they just stop. I have seen an adder before, in the winter curled up in the sun, but it’s rare. Bracken / Gorse / Heather is common territory although open forest is good as well if mixed with heathland. Sounds like you are checking hedgerows which is a pretty good place to check for them. I would walk quietly along the sun side of the hedgerow and look for them on any flattish stones at the bottom of the hedgerow in the sun. Look for a bit of sun, rocks and gorse combined and you’ll get them at their most relaxed so you can get close. But do be careful with an adder as when they are threatened they will bite and my f30 took a knock last year when I got too close to one.
I have come across a few large adder nests - they can be communal and a nest of adders even sends the shivers up me when they shoot out as a collective around you.
If you still want to look this winter turning logs and stones along your local hedgrows may turn up a rather sleepy adder or grass snake.