I don't know the market for flats and that is something you need to keep your ear to the ground on - maybe drop it to 320 and drop the offers over - but the flat has a lot going for it and you need to highlight the positives: modern, good condition and decor, amenities and gym etc; would appeal to young couple or sharers and two bathrooms means potential to rent one room out which would cover service charge and council tax, say; location, desirable county town with good shopping, John Lewis, restaurants, bars, near tube and direct to London, access to the wide Essex countryside attractions; own parking space.
A few things could be reviewed: the arrangement of furniture in the living room isn't the best; two sofas are awkward, making the dining area cramped and squeezed, yet I think there is enough room for a comfortable dining section.
Put away some of the gadgets on the kitchen surface and put on a couple of colourful accessories such as a decorative vase or a teapot and some nice mugs; even a bright towel or tea towel would liven it.
The bedrooms are not small; I can tell from the floorplan measurements that both bedrooms are wide enough to have the beds placed across the room and long enough for furniture. (I have a bedroom that's narrower than yours and it looks much better with the bed across than the other way.) With yours, though, it's hard to get a proper view of the two bedrooms from these photos: I don't know which is which. Both seem to have an expanse of white on the bed, which is crying out for a colourful rug or some patterned textile. One of them, I can't make out; is there a pillar in the room? There's some sort of reflection going on and next to it a mirrored surface.
Balcony, as has been said needs to be dressed. Lots of things you could do, for instance as someone mentioned, bamboo or raffia screening would work wonders and there are loads of other types of screening online to soften and provide privacy; other possibilities are an awning; a canvas sail; a table with parasol, colourful chair cushions and most essential, a couple of tall screening foliage plants in tubs.