A nice concept, Mike.
Not sure what software you are using (sometimes it can be pretty restrictive), but I would argue for a broader fess (it can be up to a third of the depth of the shield, and if it has charges on it without any above or below, slightly wider even) and the harp and escutcheons somewhat larger.
The helmet is a bit small in comparison with the shield – but on the other hand I have seen far too many helmets that dwarf the shield they have been placed on.
As Cygnus says, the scroll normally appears on top in Scottish arms, but your use of a harp and a motto in Gaelic almost suggests an Irish coat of arms. Follow whichever convention is applicable.
At any rate, for a first effort, this is a nice emblazonment.
You could register it in Pretoria for a modest fee.
Regards,
Mike