I don't know what a GUM clinic.
But for HIV, Herpes, Syphilis, Gonorrhea, Chlamydia you go to the Sandyford walk in clinics.
No need to make an appointment.
You go to the information desk and they give you a number.
When your number is called they will see the nurse.
Yes they record absolutely everything.
How many different sexual partners in the last year ect...
If you tell them you have been seeing working girls they will give you a Hepatitis B vaccination.
They are supposed to be impartial, but the case when I went. I got a lecture on how these girls are vulnerable women, anyway that's another story.
Of course you can just tell them you had a one night stand without protection.
But if you're seeing working girls you need a Hepatitis B vaccination and an HIV test every 3 months.
One of the nurses at the Sandyford clinic told me that you are safer with prostitutes than with Ibiza types because prostitutes take STD seriously and look after themselves.