Congratulations! Always good to know your hard work has been appreciated. Well done on your perm contract.
Sadly my work also do this secondment cover and “acting up” allowance (5-10% I believe)
Does your company have pay bandings or scales for specific roles?
Now that you’re perm you should definitely go to at least the bottom of your banding salary. It’s up to you how hard you push for over that baseline. One thing I would say is if you are going for a pay rise discussion above starting salary; ensure you have actual, evidenced examples to hand to demonstrate why you deserve it, projects delivered (timescales / budgets etc) tricky issues you’ve resolved, relationships you’ve managed/built/repaired, potential or pre escalations you’ve handled and calmed down before they explode, feedback from clients / teams / customers etc. Any qualifications, training or things as such that you have relating to your field etc. Good luck!