It is not uncommon for leases have restrictions, not allowing lets of less than 6 months. And a few local authorities are very hot on people who don't keep to the letter of the law. Here is a cut and paste from the Westminster website:
"A short-term let (STL) is the occupation of a property by the same person(s) for less than 90 consecutive nights.
Before the Deregulation Act 2015 came into force, planning permission was needed for every short-term let of a property.
However, the Deregulation Act 2015 amended the legislation and the short-term letting of a residential house or flat is now permitted, subject to 2 conditions:
- the total number of nights that a property is used for short term letting in a calendar year (1 January to 31 December) must not exceed 90
- at least one of the persons providing the accommodation for short term letting is liable to pay Council Tax at the property where the accommodation is provided
To use your property for short-term letting, you must comply with these conditions or you are likely to be subject to formal planning enforcement action."
I own a couple of flats where both the planning permission and lease allow for short term lets, but this is unusual. There is a lot of work involved as people expect hotel like standards with a full set of working equipment, so I use a holiday lettings agency. A couple of neighbours are unhappy (oddly tenants rather than owners, in my experience every block of flats has its Victor Meldrew) but there is little they can do, and I am satisfied that the tenants I attract, mainly young families wanting a beach holiday, do not cause problems. However the agency are good at screening out stags, hens, or teenagers wanting to hold a party. One bad weekend would cost a lot of money and give neighbours real cause to complain.
As well as council tax don't forget to factor in the cost of utilities and wifi. I use a firm called Insurance for Holiday Homes.