If I purchase an investment property using a limited company, can I claim the purchase as an expense straight away or only when I sell the property (whenever that would be) whether in the distant future or shortly after purchasing it? Or is it a completely different story, and do I classify that as a fixed asset? 

Arthur replies: 

You classify it as a fixed asset, as you have written (i.e., it is capital expenditure). When eventually the company decides to sell the property, all the capital expense that you have incurred now can be offset against the sale proceeds to determine the company's capital gain.