There is no risk for you of having contracted HIV from having received an unprotected blow job. You used a condom for the vaginal sex, which is safe! The fact that all the tests were negative, it is very reassuring, because through unprotected oral sex, one can contract other STIs, like Chlamydia and Gonorrhoea, but not HIV.
Regarding the HIV test, it is most likely the simple antibody test, as it is the one routinely performed by most NHS GUM clinics and this would be conclusive after 12 weeks from the possible exposure. However, in your particular case, this would not be relevant because you did not put yourself at risk.