A high platelet count or thrombocytosis doesn't necessarily means you need to see a specialist. We need to see how high it is, whether there are other parameters which are also abnormal. Need to find out if you have any symptoms which may point to the possible cause.
There is a long list of thrombocytosis like blood loss, iron deficiency, hemolytic anemia
I would suggest you see a GP first so that he can take a look at the full results, ask you further questions, examine if required.
He will then be able to decide on what is the next best course of action. You may or may not need a referral.
Regards,
Dr Taufiq