I think F and G-model wings are the same except for the indicator light housings (and possibly wheel arch flare).
If its just the outside bit shown in your pic that's gone, then it would be quite easy to fabricate the bottom section, or try to find a later good used wing (still much cheaper than a new one).
You can buy the hockey stick shaped wing support panel that sits behind it, if needed, or quite easy to make the lower part (I have a mould for the whole thing). The wing is double-skinned adjacent to the door, and flanged to the shape of the door, so it is both tricky to repair well and the metal could be rough inside the skin (the main reason I replaced mine - I didnt want them to rust through down the line after the paint job).
As someone else mentioned, if there are other rough bits on the wing, it quickly becomes both difficult and time-consuming to repair properly, so it might be better to buy new wings if you value your time. That said, get ready for a wrestling match if you do buy new...
![blackeye :blackeye:](./images/smilies/icon_blackeye.gif)