Thanks for all the suggestions! :)
Jigsaw one is £139 - bit much for me.
Love the teal RI one but not keen on the split.
Topshop one doesn't look like I could walk - looks like you'd have to walk like a pengion
Lots of the RI ones are the chiffony stuff that I'm trying to avoid, but I will definitely look next time I am near one so I can see the others in RL
HoF is good -- like the fishtail
Mint Velvet one is fine but I would prefer not black
I'm not a size 8 so the phase 8 one is no good
Asda one is good for work - as long as it is actually long enough - might see if they have it in store.