Satnav speed limit

Dinny Ken:
Hi All,
I have a garmin hgv sat nav and the eta reflects the different speed limits when in Scotland if your doing 41mph on a single carriage way it says your speeding similar doing 51 on a dual , hope this helps
I’m looking at getting a new sat nav. Either Garmin LGV770 or TomTom 6250 pro.

My question is: Suppose I start my journey in Peterhead (Scotland) and finish in Hull (and assuming I’ve set up the satnav with my truck details correctly) will either of the above units calculate an arrival time based on the actual speed limits applicable to the two countries? I can’t find any info about this on either manufacturers sites (guess that’s not surprising :unamused: ) so I’m guessing it won’t increase the trip time for the Scottish leg …

Ta,
Ken