I did the PADI open water diver course last summer, which was ace! A bit of classroom work then pool work - can squeeze it all in in a weekend.
You have to do 4 qualifying dives with an instructor after all that. Sounds like a big effort but it really builds the confidence.
Best thing to do if you're serious is do what i did. Do the classroom and pool tuition here in the UK and complete the course with your qualifying dives on holiday - I went to the Red Sea.
It's truly amazing and so so relaxing.
Hope the info helps.