Is a trademark or an industrial design the best way to protect our products?

You are not mistaken. More precisely, the external appearance and design of your products are already, in themselves, protected by copyright (1) due to only of their sole creation. A filing and a recording are not required regardless of what it can be done in the UK notably (before the IPO) to enhance protection. Moreover, you have, in fact, the ability to protect your products, especially in Europe, as three-dimensional models by a Community design patent (2) and also as a Community three-dimensional trademark (3). These two protections (2 + 3) falls under the actual "industrial property" in that they are acquired by filing and recording. So you have, in fact, three types of protection to consider in the field of intellectual property, which are cumulative, additional. Of course, certain legal conditions must be met, in particular as regards three-dimensional trademarks (by the OHIM).

To answer the following question, I would say that the protection as a Community design patent (2) is limited in time since it can not exceed a maximum of 25 years (5 years + 4 x 5 years in succession), while the one conferred by the Community three-dimensional mark (3) can be "for life eternam" if you simply renew your trademark every 10 years. this is the main difference between the protection conferred by a design patent and that conferred by a trademark., both protecting the form.

Finally, I recommend using the design patent (2) and, simultaneously, the three-dimensional trademark (more difficult to obtain) (3) because you multiply the "barriers" against potential infringers and unscrupulous competitors. And your products will be "triply" protected throughout their industrial and commercial operations and as long as necessary.

Naturally, I remain at your disposal should you need further details.