Doubts about an experimental PhD project
Do not spend several years of your life pursuing a PhD project that you aren't enthusiastic about. If you do not want to be an experimentalist, it won't do you much good. It will be a lot more difficult to overcome the challenges and setbacks you will face if you don't like your project. Moreover, it's harder to become "an expert in the field" if you're not highly motivated to do so.

However, that said, it is possible for people to move back and forth between computational and experimental work. It's perhaps somewhat more complicated now than it used to be, but it's still certainly doable. Unfortunately, it may take some additional convincing to show people that you want to be a modeler if you've only done experimental work.