Hi,
I am not a lawyer, but I believe your dad can view some parts of your medical record IF YOU GIVE WRITTEN CONSENT FOR HIM TO DO SO. There are a number of levels of access to patients' records in, for instance, Vision [one common software package used by GPs in UK - others are Emis and Toris] - if you ask your GP receptionist to provide you with your login details, you can access certain parts of your medical record yourself [depending on the policy of your surgery], which you could show your dad [since it is clear that you are happy for your dad to do this].
M (ex medic)