im doctor and i got a student visitor visa to do a medical membership exam, the visa is valid for 6 months and cant be extended as the immigration laws says

i'm new to this site and i really would appreciate any helps from the experts here on these 2 question

1 if i get a medical registration in a training unpaid job can i stay in the uk on this visa up to 6 months

2 if i intend to change my visa to another category after i get a training position as a doctor is it possible to change my student visitor while i;m in uk or i have to get out of uk and waite for another 6 months until i can apply

i really wish you guys can help me with these question