Sonnet, here is my advice (and bear in mind it was me who said Monsoon )
Firstly think of colours, because you want a base colour which you can add to. Mine is brown this year, so I make sure everything I buy is brown, or goes with brown (inc turquoise and hot pink they do go with brown!) You might want black to be on teh safe side, but black and strong colours are never as funky as other combiinations (hence brown for me, it also goes with black)
What you need is a good skirt. Don't go for the gypsy look for work, you are too short (!) and it is not a smart enough look. Look for a circle skirt that cuts off on the calf. Basically a nice print could be fun and funky (I got a great one from Monsoon and I don't usually shop there) also look in other places like Wallis - they have a great Black and White one at the mo (also petite sizes so a good length)
Secondly a nice pair of trs. There is a lot of Linen mixes out there - linen mix doesn't crease like linen (I don't iron EVER) and looks fresh. I have a fab pair form Tesco £18 (20% off atm) which are brown
Thirdly look at the new crop trs - but only if you are comfortable at work in heels (wedges are great) as you need heels to make them work. Next have some nice ones, again petite lengths for your height. Go as wide as you can as they look better.
So 3 bottoms, which all have one base colour - skirt can be pattered.
Add loads of twinsets (see other thread) fitted T-shirts and at least one nice wrap cardi. And a pretty chiffon Kaftan top - see through is fine with a vest underneath.
Shoes - wedeges will go with ALL of the above looks, as will jewelled flat pumps - New Look £20.
A funky low slung belt will work if you also get a couple of longer t-shirts/Kaftans. Too chunky on't work, don't go wider than a couple of inches (again New Look). Funky bags look at Accessorise (expensive) or places like Peacocks, Primark, New Look (sometimes)
I reckon that gives you 3 outfits, with a million combos and should easily be less than £250.
PS I don't charge much for advice, I am just telling you what I have bought recently. But I wear casual jeans to the office, smart casual for meetings. I can wear boho to work too, but that is because I work in media