If you have a gap between your front teeth, it can be closed with any kind of veneer. If the gap is more than a couple of millimeters wide and you only have veneers placed on the front two teeth you will end up with 2 really big teeth that are not in proportion with anything else in your mouth. This can sometimes look worse than having the gap in the first place.
Usually when someone comes to have consultation with me I will suggest that at least the front four teeth are restored so that the end result is pleasing. The last thing you want is to spend the money on the front 2 teeth and then be dissapointed with result. If you were then to have four teeth restored you would then have to pay all over again. I would seek the advice of a cosmetic dentist that carries out these treatments on a regular basis. Have a look at the treatment portfolio and ask if an image can be done of your teeth so that you know what you would like after treatment.
You can of course have your teeth whitened but this is an adjunct to veneers rather than a replacement for treatment
Kind regards