Legal advice grandparents visit grandkids

Hi All

I lost my husband some time back and been having not having the best relationship to my in laws. They were seeing my kids regularity as in every 4-6 weeks. They are being demanding to see more often and wanting them go their place and visit them during weeks to do School run etc. I denied as we can't practically do this as we have life too and it seems they are trying to see my kids replacing their loss. We are going through mediation and maybe they will take me to court. What is thoughts on this? How fearful should I be considering the UK family law?