You CAN hunt rabbits with dogs, they are as above exempt under Schedule 1 of the act:

Rabbits

4 The hunting of rabbits is exempt if it takes place on land-

(a) which belongs to the hunter, or
(b) which he has been given permission to use for the purpose by the occupier or, in the case of unoccupied land, by a person to whom it belongs.


You CAN use dogs to kill them:

http://www.defra.gov.uk/rural/hunting/hunting_qa_c.htm#18

also always carry a wriiten piece of permission given and signed by the owner or leaser of the land