We are a smallholding on half an acre. Although you have to register with DEFRa if you have over 50 chickens, you can still register with less than that.
When we first moved here we had 2 goats, so Brian called DEFRA, but we were already a smallholding at our previous house with only a fifth of an acre! They gave us a Holding or CPH number, then for the goats we have a herd number and for the chickens we have a flock number. But now we only have the chickens! Then we just let them know if our numbers go over a certain amount.
Its very easily done and doesnt take long!
Good luck with your 2 acres! Dont let them grind you down. We HATE planning officers and councils!!!! They are a pain in the butt.