Hi Cian,
Yes you are correct the inch pedal will disengage the drive. If you need the truck to stop on a slope you can use the emergency brake, or alternatively you could get a switch fitted to the inch pedal to auto engage the brake (usually a 3 to 5 second delay allowed).

As you are in Ireland, the Irish team here are more than happy to help you. You can call Combilift directly and ask for the Irish service team or, you can complete a quick technical support form at the bottom of the main combilift.com web site or direct link https://warranty.combilift.net/technical-support-form/. The form only asks for the minimal info so the team can quickly help you. There is no login required and no charge for this support.
This will go direct to the service team (it goes to the team assocaited with your country).
Plaese contact us today and we can advise next steps.

Thanks
Richard