Can my landlord enter my flat without my permission?

[giulio]

My landlord is arranging viewings to sell the property I rent. They want to come at a time which is not convenient to me and I have offered several alternative dates for the viewing. They are insisting they are still coming and gave me 24 hours written notice. I explained the reason they cannot come on a particular date is that I am revising for exams I do not want my peace disturbed. By not getting my permission are they breaking my right to quiet enjoyment of the flat I rent?