Heterosexual HIV transmission in
the UK occurs mostly among immigrants from AIDS
-endemic area, like southern Africa
. Even among CSWs in London, only about 1 in 1,000 have HIV -- so the chance your partner had HIV is extremely low.
Therefore, from a strict risk-assessment perspective you didn't need HIV testing at all; the benefit of testing is purely from the psychological support you should be feeling from knowing for sure that you didn't catch it.