Conditions of Employment after handing in notice

I intend on handing in my notice in early March giving a two months notice period (as required per contract) before leaving. According to my contract the company will pay my annual retention fee which is due end of March. This fee is compulsary and failure to pay will result is cease of registration and I will no longer be registered to practice in the job.

What I'm hoping to find out is must the company pay the fee according to the signed contract? Or as a result of me handing in my notice does this effect terms and conditions of my contract i.e. can they refuse to pay it?

Thanks