My work place making me doubt my own rights!

Can anyone help me please, So i live in the UK and am currently pregnant (6weeks) so im getting appointments and my managers at work are saying they will not pay me for these appointments and that I need to make up time for them later on.. apparently its at the managers discretion wether i get let to have time off... on the government website it says completely different.. what do I do? Can someone advise me?