Second Home Temporary Time Share?

I currently own my own house in England, where a very good friend stays with me as a lodger. I also have a (very) modest BTL portfolio of one other property in the same area, which I would eventually like to add to. Both properties are mortgaged.

In around 2018, my job will require me to be based in Scotland for 3-4 years, so it seems to make sense for me to buy a second home up there with a view to renting it out afterwards. I would like to keep my current home as my main residence throughout my temporary stay, both for CGT purposes (significant slice of capital gain at stake!) and for practical reasons (i.e. visiting friends, storing most of my possessions, etc.).

I will have work-related accommodation provided in Scotland for about half of each year, so I would ideally want to have a ‘time share’ arrangement with one of my opposite numbers, such that I would live in the property for half the time and they would rent it at a very reasonable rate for the other half. I am sure any potential sharer would be happy to rent on the basis of a fairly informal arrangement (e.g. a lodger agreement); however, I am not sure if this would be possible, since I would only really be looking at buying a one-bedroom property – we would therefore be limited to taking it in turns to have exclusive access.

I can already envisage some of the cans of worms that this arrangement might open with regard to mortgage conditions, Scottish tenancy law, tax liability, etc.; so, my questions are:

* Can this be done, or is there one or more complete show-stoppers?

* Is it as good an idea as it seems to be to me, or does it look like more bother than it’s worth?

* Can anyone think of a particularly neat/tax-efficient way of doing it?

Many thanks,

Lucan