how can i not be afraid at going in to see my GP

i recently had some blood tests done and also started a new antipsychotic medication...anyway my gp surgery has been trying to get hold of me and contact me...and ive not answered the phone because i'm frightened of doctors and anything medical or clinical......but the surgery rang again yesterday and a picked the phone up and answered it....and it was just a gp receptionist or admin worker saying the gp wants me to go in next week to see them for a routine appointment, regarding a letter?

so now i'm frightened what the gp wants to see me about now.....could anything be wrong with my bloods or is it about my new meds i'm starting? so i arranged an appointment to see my favourite doctor, he's a very nice warm friendly doctor, so i'm thankful for that....but i'm just scared what they want to see me about?

i do manage diabetes type 2 and did well years ago by getting rid of it through diet, and exercise, i lost 4 stone......but ive not been at swimming at the gym for over 6 months and ive gained weight again around my stomach...so i'm frightened they want to see me because the disease has come back?

i'm in limbo at the moment, and the not knowing is driving me to panic stations.

how can i man up and not be so afraid at going in to the surgery where i feel so much fear?