Honestly I never picked mine up. I hated my school by the time I left and was too anxious to go back to collect them. I have my statement of results which has been fine. If I ever need my certificates, I'll apply to get replacements, but I've not needed to in the 10 years since I left secondary school
Edit: I've just googled it out of curiosity and according to the Gov UK website, you can't get replacement certificates, only certified statement of results. So I'm all good