Soon I will be moving into a flat with a gas hob, and I've only ever had experience with electric hobs before.
What do I need to be aware of in terms of the differences between them? I've heard that gas hobs tend to heat up more quickly - is that the case? If so, will I need to adjust cooking times?
The main difference is speed that it changes temperature. So when you turn the hob on it is at the heat you turned it to almost immediately, if you turn it down it is cooler that second.
This won't take long to get used to but if you have recipes which say something along the lines of "Bring to the boil before reducing to a simmer" you can now do exactly that as opposed to the best approximation electric gives.
Another important thing to note is that you want the flames under the pot, not going around the edges: so you need to use the right size pan; usually you want to put it on the largest ring which means the flames are under. If flames do go around the edges you'll find pan handles won't last long and you might have more trouble getting the temperature you want.
You will also find that you have more flexibility with choosing new pans as the thermal contact isn't just at a flat surface: woks, or pans with ribbed or curved surfaces will work better. Pans you might not have liked much before could become new favourites!
You'll love it, I don't think i could ever go back to electric.
Overall, most of the enthusiastic cooks I know prefer gas because of the better (ie. instant) temperature control.
However, one downside of gas ranges is that they often have trouble with providing very low heat because if you turn it too low, the flame will go out. Some gas stove tops will have a special "simmer" burner that is smaller and that you can turn down quite low. We use ours when cooking rice ... we'll start it on the regular burner to bring it up to the boil, then move it to the small "simmer" burner for cooking. When we tried leaving it on the regular burner, even turned to the lowest level, it would still bubble over. Of course, due to the instant response time (ie. there's a flame or not), it's no problem to move pots around like this, unlike on an electric range, which you'd need to "pre-heat".
You also have to be more aware of fire hazards since you have an open flame. So be more careful in terms of cleaning up grease and when using alcohol in cooking (don't pour from the bottle is the usual advice because you may catch the contents of the bottle alight if you're unlucky).
As someone who did this several years ago, I can tell you that there are two main differences.
Most electric plates have much higher thermal mass, which means they change their heat level quite slowly. In practice, this means that on gas your pan is going to be ready to use noticeably quicker and when you turn it down, you only have the mass of the pan holding heat.
Electric plates at full can be hotter than gas hobs at maximum. The very cheap electric range where I'm currently renting have no thermostats on the plates and I was constantly burning things until I realized they got hotter than the gas hobs at my previous place. Or even the glass ceramic plates at my parent's place.
