While transmission between female sex partners is rare it is not impossible.
If you have had sexual contact where your blood or sexual fluids is likely to have entered her bloodstream, then she may wish to access treatment that will minimise the likelihood of acquiring HIV. This is called post-exposure prophylaxis (PEP).
She needs to go a medical centre or emergency department of a hospital and ask for PEP. Treatment is more effective the sooner that it is begun. It must be commenced within 72 hours. There is a national list of services where PEP is available at www.getpep.info .