Thank you everyone , I will call my midwife as my GP surgery is in a different borough to my chosen hospital and am unsure as to how this might affect me obtaining one from there. It's is very confusing!
I was so relieved to get good news at my 20 week scan (last pregnancy ended due to bad news at anomaly scan) that I skipped out of there without asking for the bloody form!
I had to go to the hospital reception desk with my hospital notes and anomaly scan report, they then got a random midwife to collect my paperwork. Might be working checking with the hospital reception as it might be something you can just pop in for.