and so normally wear a size 12 top and 14 trouser... but my (size 34) hacking jacket definitely seems quite roomy around the waist (and normally also the bust by the time I have 'em strapped down in a sports bra!
)
Sorry this probably hasn't been much help, it may be best to get to a local store and try some on?
34 is 34 inches round the chest, normally it would be 10/12, but it depends on size of your..ehm.. boobs and the cut of the jacket.
For example I'm size 12, but thin waisted big boobed type, so my jacket is 36 inch and taken in at waist.