I'd say skip the car, but not for that reason.
There are very few places we've been so far that I'd advise no car, but Malta's one of them. We do fine driving on the left in the UK, and fine driving on the right w/the intense aka crazy drivers in most of Italy - but our experience driving in Malta was hair-raising, not to mention there are no road names or route numbers, making it really hard to navigate.
Buses trump everything on the road, they don't slow down for cars or pedestrians. There are many poorly-signposted roundabouts, and drivers there don't like it when you circle around more than once - we felt we needed to know which was our exit before we started into the circles, which was impossible. In fact we often didn't know the correct exit after 2 or 3 times around.
You have to take out damage insurance, your cc won't cover that - but we didn't take the extra lower-deductible insurance. We paid extra to park in the parking garage of our resort so as not to risk it getting hit in the street. We left it in the garage for our first couple of days there, using buses only, since our road trip from the airport to our resort was so difficult (didn't help that it was dark and raining sideways). When on day 3 we decided to venture out, we discovered it had been side-swiped in the parking garage. (Fortunately the rental car co. didn't penalize us even tho we had a deductible - I suppose because that kind of damage is common there.)
The buses go pretty much everywhere you'll want to go, using Valetta as a hub, and are very cheap. Also we found some bus drivers very helpful in giving us walking directions from the bus stops to the places we wanted to see.
We thought we'd need the car to get around Gozo, we ferried it over, but even there, I think the bus system was pretty good.
I bet the resort can give you instructions on best way to get there if you email them, using the bus system - or I'm sure you can take a taxi.
