There are 3 aspects which determine how employers see you
1. Your availability
if you have no availability in your Schedule then practices will not see you in their availability calendar
https://gpnetworks.co.uk/schedule
2. Your visibility
If you have no visibility connections to practices, practices would not see you even if you had availability
https://gpnetworks.co.uk/connections/manage_practice_visibility
3. Hub connections (Connect from the Hub Work screen)
If you have Hub connections then you can have custom visibility and availability to Hubs, distinct from that which practices see – Hubs can assign you if you have Hub availability
https://gpnetworks.co.uk/hub_management