Yes that's correct, after a successful proficiency check the examiner can sign the licence (as long as the rating is still on the front) and you're good to go. The examiner emails SRG 1157 to the CAA, no fees are due to them.
If the licence has been re-printed with the expired rating on the back then you'll need to apply to the CAA using SRG 3108 and pay the £96 fee.