I would agree with others, you basically have two choices A. cover them up for the rest of your life, your practical tutor may well allow you to wear long sleeves if you explain (or just roll them up last minute and keep your arms turned away) or B. accept you don't want to cover up for the next 60 years and just wear short sleeves and be prepared if anyone questions it, something like 'they're old' usually does the trick
I wear long sleeves most of the time at work as I work with vulnerable teens and I don't think it's fair on them or something I want to deal with... but I wear short sleeves on work do's, in the staff room, after hours etc... in two years I've had one double take and one person asked what happened then frantically apologised afterwards as they didn't see them properly and hadn't realised