I've just Googled Dawn French as I always think she looks fab but not like she's trying too hard.
Had a look at a few photos of her and she seems to stick to a trusted pattern of colourful long top and black wide leg trousers or a colourful long coat over a black top and again the black trousers.
I realise she's quite a few sizes bigger than you but she does seem to like to keep her legs under wraps. What do you think of what she wears?
Now I know this coat is probably more suitable for Spring and I'm not suggesting you rush out and buy a carbon copy but can you see that it's near enough impossible to find and fault with her figure? I'm not even looking at her body as she has a lovely friendly face and the coat is so eyecatching that I'm not looking at anything else she's wearing.
If this is a look you think you might like to try then I found these wide legged jersey trousers and this really pretty long top. Or you could wear a plain black top (Pack of two here. One black and one grey) with the trousers, again a la Dawn, and then a really bright coat. I love this one! Don't forget it'll be longer on you than it is on the model in the photo. If you don't want to go that bright then a classic trench would look good instead.
Like you I have big boobs and find that a big expanse of fabric across my chest just makes me look bigger so I know that lower necklines or v necks are the most flattering but another trick is to break up the chest area visually with jewellery or a scarf. It also gives the eye something to focus on. Even something as plain as this M&S necklace worn over a black top would break up your top half. If you want something with a bit more "wow" then this one is very pretty.
I think Heated's suggestion of a cardigan is also a good way to go. What do you think of this one? It only goes up to a size 22 but it's a loose fit so that should be fine for you if you do like it. And don't forget it'll be longer on you than the model.