In the ideal TN-S case, yes. A fault on neutral has no impact on the E connections.
However, in reality most DNO networks are not "pure" with only an ideal case, so what looks to be TN-S at the home cut-out could actually be TN-C at some point between there and the transformer (where ideally the N-E common link is located).
In most cases the best route is to connect the earth/CPC together, as most out buildings won't have extraneous conductive parts to worry about and most will not present a risk even if there is a PME fault.
The armour would then be glanded at both ends for a good connection. But you might still need to use 3-core for a copper CPC, or to have an external CPC run along side the SWA (might be cheaper, not a good approach unless in duct), for the following reasons:
- If PME and extraneous, to meet the 10mm copper equivalent minimum
- To meet the Zs for sub-main and/or final circuits disconnection times
You need to get to around 70/50/35mm for 2/3/4-core for the SWA armour to be "10mm copper" equivalent, and for even moderate lengths of typical sizes (like 4-10mm for modest loads/medium runs) you can find the sub-main R2 is too high for acceptable disconnection on the armour alone.
The main home also has the PME risk, but it should be adequately bonded for water/gas pipes, etc. With a 60-100A main supply and incoming cables of 16-25mm you would not really look at less than 16mm for main earth and 10mm for main bonds anyway.
The PME risk is really about voltage differences. Inside a home with
adequate bonding you don't see the "true Earth" to get a shock. Outside where you have access to the CPC and the Earth you have that problem.
So it is not that the main home is intrinsically safe and an outbuilding unsafe, but more likely an outbuilding will be used for outdoor stuff, hence the greater concerns.