I’m not a strong swimmer, is this going to be a problem?

You don’t need to be Michael Phelps to learn how to dive but there are some minimum requirements for safety reasons. You will need to complete a 200meter swim (any stroke and it is not timed), you will also need to “float” for 10 minutes (this can be laid on your back, swimming or treading), you will also complete some snorkelling skills. The most important consideration is that you feel comfortable in the water. If you are not there yet then taking a couple of swim classes will improve your confidence and overall enjoyment.