Hi Joanne
Really good question, and I'm sure someone will have an informed and solid answer for you if mine is wrong.
As far as I'm aware, you can go to your GP and request a blood test for the required vaccinations to see if you are still immune and whether you would need a booster or not, or even a new course of vaccinations.
Although I had a record of all vaccinations and the BCG scar, I still needed the results of my blood work for TB to show my employer that I'm still immune.
Hope that helps!