I'm an avid gardener as well as have found ticks on myself but never became reinfected. I actually had a tick attach itself inside my belly button a couple of summer's ago and nothing happened. I am bad, I don't use any protection. And I'm not going to cover myself up with clothes when it's really hot out.
Call me stupid, but I really believe the best defense is a really strong immune system. Of course it doesn't hurt to use Neem or other products, I heard Avon's Skin so Soft is good (I use that for mosquito's and flies when I go to the beach). I know you live in Europe, do you have access to Avon products?
Wish I could be of more help,