BASHH, the British Association for Sexual Health and HIV, I find are the resource for managing GUM conditions. Listed in this link are all their current guidelines. A vital resource. Just do remember to check on local resistance rates, particular with ref to Gonorrhoea.
Travelling the world….
TRAVAX is a good site outlining what vaccinations people need and where. You do need to register to access it, but is free if done so.
NathNac are an agency similar to the above however they can give advice on the phone for those more troublesome and unusual questions
Part of our role is to inform public health of the notifiable diseases. Here is a link to the HPA site with the form on the right.