A friend of mine has recently become a platelet donor, there is an urgent need for this as not everyone is able to donate platelets. They have a really short shelf life too so your donation will be saving lives within 5 days!
I've been told anyone can be tested for suitability at their next donation session; you just need to ask the nurse during the question and finger prick session and they draw off an extra vial for testing during the donation.
Worth a try
linky to info