If you’re covering the whole journey, not just the part in France, I don’t think it makes a difference.
The “general rule” for B2B cross-border services is that the place of supply is where the customer belongs. Suppliers based abroad invoice without VAT, and customers account for VAT using the “reverse charge”.
If your service was considered to be related to the shipping, HMRC’s Notice 744B, section 3.2, says that the place of supply follows the “general rule” unless the shipping was entirely outside the UK:
But if your service was not considered to be related to the shipping, it would still fall under the “general rule”, as none of the other exceptions seem relevant.