Apologies for the late reply - been sunning myself up the Northumberland coast
The 30 amp fuse will give more protection than the 40 amp, but what I've found is this:
If the leisure battery is dead flat, the alternator may charge initially higher than 30 amp so the fuse pops.....a 40 amp fuse should prevent this.
If there's a direct short, any fuse should pop anyway.
The secret seems to keep the leisure battery charged up from a mains charger from time to time.
Now, from memory, the fuel pump fuse was underneath the dashboard, midships inside....within the usual fuse cluster. I have no idea why it blew - just the van wouldn't start after.
If I remember any other foibles I'll let you know! Danbury most reluctantly replaced some of the external chrome parts (mirrors, head lamp bezels etc) after 9 months due to rust but it was like getting blood out of a stone.
I think there's quite a good unique vehicle under there actually - its just the build quality has to be looked at carefully.
John