I would find that kind of investment dangerous. You would be putting all your eggs in one single basket. I would diversify across a range of assets. Take different pension plans with different companies. Try offers from life insurers as well (in case you die prematurely, does your family have enough to live on comfortably).
Also, you effectively have a second job as landlord and are responsible for repairs and maintenance, which can also be risky. I know you are a dab hand at DIY but a botched job here or there can be a huge financial burden (I'm thinking plumbing, fire through bad electrical installation, etc). You will need to be able to respond immediately to problems, which is probably what you need to do for Rockall too. Imagine your tenant calling about a broken pipe and your largest client calling about a broken website which needs immediate repairs - on the same day. Where do your priorities lie?
You will also need to calculate the cost of refurbishing the house back to a level where people would want to buy it. Think about it. In Switzerland this would mean a shiny brand new kitchen, new baths, everything painted afresh.
The one possible argument for a house is that it essentially forces you to save, but since you don't seem to have self-discipline issues, I would vote against it.