Polyhydramnios - help!

Joanne
Hello all - I'm from the UK so things may be different elsewhere. 
I have just been to see my midwife and she has said she suspects I may have 

Polyhydramnios (too much amniotic fluid).  I asked her what is done to confirm this and she said a scan. After much debating (on her part) she had decided not to send me for a scan and instead see how I am at my new check up. 

I'm really worrying now and don't feel reassured at all! Has anyone else had this and what investigation was done to see if it was actually polyhydramnios? I just don't feel comfortable 'waiting to see'. I'm 36 weeks now. 
Thank you for any advice