An instructor for a day is a great idea if you only sail a cruising boat every few years. They aren't that expensive (inexpensive actually), particularly in the context of a week long charter. If I leave with full fuel, I've never needed more on a one week charter, so I'm not sure why you feel pressure to conserve so much. I would practice techniques, such as anchoring or picking up the mooring, that would allow you to relax and not be forced into situations you prefer not to be on vacation. I would think you could refresh those with an instructor in just a matter of hours. In many cases, you will then be able to motor in, take a look at the fuel/water dock before you decide if it is an approach you're comfortable with. If so, give 'em a call. If not, go pick up a mooring or drop the hook.
If I recall correctly, there is a fuel/water dock in North Sound on Virgin Gorda (Leverick Bay maybe?) that is a grounder (big long unobstructed pier and can pick your side for wind) and North Sound has plenty of easy places to anchor, as long as the wind and fetch are not out of the north. Nothing wrong with waiting off until the pier clears to your satisfaction.
If the experience become more stress than relaxation, I would not bother with Anegada at all.
Have a great time.