Thank you all for your replies
I have done some sums - checked with my future customers and the following is what we are going with:
Chickens (copying Sylvia

) - Slaughter, Pluck, Gut, Package
1 - 10 @ £2.50
11 - 20 @ £2.00
21+ @ £1.75
Ducks, Geese, Turkeys & Game - Slaughter, Pluck, Gut, Package
£2 per kg
Hanging£0.20 per day
I will see how this fairs this year and if needs be adjust
Thanks again for your help