So I have a question about what moves are allowed in the following situation:

England has a fleet in the Baltic Sea region (forgive me I don’t remember the SZ no.), which includes transports. Germany purchases submarines on its turn, making the SZ hostile.

Can england use its transports to move out of the hostile zone, pick up troops, and then move back in to the hostile zone (and then conduct an amphibious assault as normal if the subs are defeated) or must the transports, if they retreat, end up in a friendly sea zone? Further (and related) are there ANY restrictions on movement caused by starting in a hostile zone rather than a friendly?

Thanks.