i wrote a reply here but it doesnt seem to have posted.
I liike the idea and think it would be fine. But i'd probably cut a few ingredients. Theres just a lot going on here with the sausage, orange, fennell, chicken, mushroom, white bean, carrots, not to mention truffles and foie gras!
Id try and make a garnish that harnessed what is inside of the wellington. Like, if it will have a strong taste of the orange and fennell, why not make an orange suace of some kind, or braise off some fennell and saute it. if its in the summer, shave some fennell and make a salad. make a roasted fennell puree etc etc
I like to keep things to a few differant flavours so you know what you are tasting.
If i was trying this it might go something like
Chicken, manchego cheese, parma ham, duxelle- stuff cheese into chicken and wrap welly up as normal. Serve that with a chicken reduction, then just some seasonal vegetables and perhaps some nice mash or whatever is going at the markets. Simple, it all works, and you will be able to taste everything that goes into the dish.