As Kayakebab we get ours from Dinah at Denar next to McDonalds in Fethiye. This year Buildings and Contents came out at just over 450tl, for a 4 bed detached, not forgetting the DASK (earthquake insurance) which is another 180tl or so. I'd say cheaper than the UK, but prices of insurance in general are going up fast in the last year, so the gap could be narrowing if you are serching around for the best price/service in the UK.
Having said that Dinah will usually offer you three different qoutes from different insurance companies, a number of which you will know from the UK...although they are French and German companies!!