User Research: Checkout redesign

I work at a retail company and am about to start a redesign project - I'll be looking at checkout process.

I don't have any personas in place and the company doesn't have the money to invest on this. So, I'll:

1.take a look at customer feedback

2.speak to the Call Centre asking about customer issues around the checkout.

3.speak to our Web Analyst and look at Google Analytics to understand Bounce Rate etc

I'm thinking that I'll create a number of provisional personas (probably 2), then conduct a Customer Journey Mapping exercise.

Does this approach make sense? Is there any other technique you would recommend?