We have lots of Rightmove alerts and every now and again I check Zoopla, Primelocation and Globrix but generally, apart from on the very odd occasion, nearly all of the websites have exactly the same properties.
I find www.home.co.uk sometimes turns up different properties and has a good search function.
Do you have any other sites, maybe even for private sales - anything!!! - that gives an alternative source of properties but which is not rubbish like gumtree, or mypropertyforsale or housesimple...