I think you should think about ringing NHS direct and they will put you through to a doctor who might be able to help. Tell them what the reading is and they should put you through to a doctor.
I could tell you what I personally would do, but I don't know if what I'd do is the right thing to do, if you know what I mean! So I think you should ask NHS direct. Warning, you need a lot of patience when speaking to them - the people who answer the phones are reading through a flow chart on the computer, they will ask you about lots of seemingly random symptoms, try not to get too irritated.