Hi,
yes you wil partially serve some of your sentence in a Young Offender Institution, and then transfer to an adult prison once you reach 21.
A Young Offenders Prison is similar to an adult prison with an emphasis on rehbilitation through education and sometimes work practices. However, with a short sentence of around two years it's unlikely you will engage in any courses because you will be released before you can embark on them.
When you first enter prison it's daunting. I was subjected to incarceration on remand in Feltham when I was 15. I was driven in a hot prison van or 'sweat box' as they're affectionally known, and placed in a waiting room with other convicted and unconvicted prisoners.
Because of my age I was anxious particularly because some of the others were around 19 - 20. You are fed, stripped searched and returned to the waiting room. When called you are subjected to a short interview regarding your offence, habits (drugs etc), aspirations while in prison, then taken to a designated wing and placed in a prison cell (single or multi-occupencey). It's a very humiliating and clinical operation.
The following day you are shown around your new home.
It will be an anxious and nearvous experience at first, but you will settle in quickly I promise you. And just remember a short sentence of around two years means you will be released after just one year (providing good behaviour).
Hope this helps, keep us informed of what happens.