Preheat the oven to 180°C.
Cut the fennel into long, chunky wedges.
Crush the fennel seeds using pestle& mortar, then add the garlic and crush again. Add the butter/spread lemon zest, plenty of salt & black pepper. Mix to a paste.
Put the chicken in a large baking tray and scatter the fennel around it.
Using your hands, rub the chicken all over with the spiced butter (including the cavity), then the fennel wedges. Put the chicken breast-side down into the tray.
Cut the lemon in half, put one half in the cavity and squeeze the other half over the fennel.
Roast in the oven for 20 minutes, then take the tray out, turn over the chicken, letting the lemon juice out of the cavity. Pour the wine/stock over the fennel, baste well and put the tray back in the oven.
Roast for another 70-90 minutes, until the chicken is cooked through and the skin is golden brown (check with a skewer - if clear juices are running out of the thighs, it’s cooked through). Do baste the chicken and fennel a few times during roasting!
Remove the chicken onto a plate, cover with foil and kitchen towel to keep warm.
Put the fennel into a serving dish.
Reduce cooking sauce into a thick gravy.
Carve the chicken and serve with the roasted fennel, gravy and side dishes of your choice.