Thats exactly what i did on my PvP Shammy, and I would recommend it to you especially if you are very social/friendly (you will be leveling/finding parties very quickly and lots of people will have you on their friend lists ) and/or want to learn how to PvP well from the very beginning.
You can, if you want, switch to enhancement/elemental later on when you gear up (or you might fall in love with resto and stay there forever). Also, getting party/raid spots and therefore gear will be much easier as resto, and if you develop love and taste for that style, you will be both much better healer and there will be no feeling of being pidgeonholed into it. To put it simply, you will enjoy playing as opposed to forced respec/grind for gear.
If you decide to go resto, first learn how to buff (shaman is, by far, the strongest buffer in game). Learn your totems (you have 25, read tooltips/cooldowns/range/school carefully and after some practice you should be fine). Learn how to twist totems of the same school (say, WF with Grace of Air or Grounding or Tranquil Air), bind some, use 'em.
TLDR: dont level as resto, PLAY as resto.