For vaccinations, we found these two sites extremely helpful:-
We also sort advice from our pharmacist & Doctor/nurse. As many of the vaccinations required are not available free on the National Health. We had to make sure that we were not having vaccinations that weren’t essential. Vaccination costs run into hundreds of pounds each.
Some countries will not allow entry without a certificate/proof of vaccination. Start any vaccination program early enough, as some live vaccinations (e.g yellow fever) can not be taken within a certain time period of other vaccinations.