I was prescribed Loceryl by my GP for my big toe nail. Its quite expensive so better to get it on prescription, and ask for 2 lots at once so you only pay one charge - i have found that it is effective, but you need to apply it once or twice a week, and dependng on the depth of the infection, it can take months to get rid of properly, or it comes back.
If you start and dont keep at it, it will will reappear, mine is very nearly gone now.