help finishing off window trims/cils

Windows were fitted by a company but due to problems, they ditched the job and now I have windows fitted, but just need to finish them off.

Ive done the windows cills for the flat windows. and use d-mould trim to cover the gap between the window and the old timber frames.

On the bedroom bay the window sits on a timber frame, and the back of the external cill can be seen, which protrudes slightly more then the wall. How can I finish this off with a small window ledge?

Also between the wall and the window, what trim should be used, I was thinking of using a thin t-piece trim. what this be ok?

I know its alot to take in, and appreciate any help

Thanks

anyone help?

A couple of pictures might help.

i think you want window board, not an easy job on a bay with angles.
post photos, you haven't said if they are timber or plastic.