Grahama,
I concur with "Pace" on this one.
I've flown this route ferrying a twin (+tanks) and its a lot of water to cross and weather changes fast.
Some years ago a Dutch lady flew her Grumman AA5 to Iceland. She would not be persuded otherwise. First year she made it, second year the headwinds were a shade stronger and she ran out of fuel and crashed into the water a few miles short. She was in a dry suit and swam to shore. Her co-pilot narrowly made it.
If you decide to go for it, measure the Robin's fuel burn and oil requirements. Add extra headwind component. Diversion is Faroe, however Faroe can suffer fog, etc. Make sure you can get in there on instruments. Also carry the instrument charts for Iceland.
For survival you have got to get into the dingy with the EPIRB+gps. Remember its outside heli range, so survival is up to you. Expect at least 24 hrs for a ship rescue.
For single engine low speed aircraft your'll be pushing your luck.
Why not try the fjords of Norway?
flyme