I say give it a test drive and see what you think. I think it's largely personal preference. There's a few situations where I don't like autos:
- if you are going up a hill at a speed that isn't perfect for what the car wants, they tend to jump back and forth between gears
- if you are going down a hill, it will continue to shift up, so you need to apply the brakes to maintain speed
- if you are stopped but in drive (i.e. at a stop light), the car will drive forwards unless your foot is on the brake
- if you accelerate, they tend to downshift even if all you wanted to do was gently increase your speed
Overall, I feel more in control when I'm driving a standard. I find that the major advantage to autos is that it's easier to drink coffee while driving

.
As to economy, I think that they are less economical. First off, you do have a bit of a hit in fuel economy - depending on the car, it can be as much as 4-5 mpg difference. I'd say look up the rating online somewhere (for example,
Fuel Economy is pretty decent for North American cars, but I'm not sure if there's a British equivalent). Secondly, I think (not sure though) that autos are more expensive to maintain/fix.