personally i think its important to even just learn bother, your apprenticeship is about leaning as much as possible in your 3 year, you may not like a particular aspect but learning it is important, you may even like it once you know what your doing. i love my cutting to probably a little more then colour, but being able to learn both (well) has been a real help. once you have the knowledge and confidence to decide on what you wont to do then do it but give it a shot.
and be happy to even be given the option to learn both, some places wont give you the chose to do both.