Surfing Waves

Hiya, I'm 16 and have been surfing nearly a year now. Looking to build a fish for a school project however I have no clue on sizing, I'm 5ft4 and 56kg surfing on the isle wight waves are pretty small. any advice on sizing and anything on board building would be rlly good

5'10" x 21 1/2 x 2 1/2

Are you going to glass the blank yourself or just shape the foam blank and have someone else glass it for you ?