It's no longer required to take antibiotics before dental work - and you have a chance of actually swallowing the bacteria there.
I'd say, nothing is needed. Make sure you're going to a good studio that does sterilize everything properly (don't let a friend do it, they can't autoclave everything). If concerned tell them about your heath problems. A good shop and tattooist will know to be careful.
If you're still unsure, give your doctor a quick call.