Window sill repairs - fillers and stains question

[novice81]

I'm repairing a wooden windowsill and just can't get the perfect match of filler (ronseal natural is too light and ronseal light is far too orange!) Have tried mixing the two in various concoctions but is still a little bit light/orange and I can't get it exactly the same. Will this change once I stain / varnish it or will it show through? And is it better to use a clear varnish or stain it darker. i.e will the filled sections stain different to the rest and still show up even if I use a darker shade?

Please help, I am about to just completely give up and paint it if there is no solution!