I live in a very VERY small community where people drive short amounts, maybe 1-2 miles per trip without warming up their engine. Some residents leave for 9 months of the year before coming back to do the same amount of driving. I've had about a dozen so far come to the shop with fuel related issues, usually rust deposits that make their way into the fuel injectors.
Additives are a tough sell for me as far as gasoline engines goes, I wouldn't bother pouring one in *unless* your fuel tank is below 1/2 and you plan to leave the machine parked for a year. Only then would I pour in a methanol based alcohol (known as HEET in the US). The purpose is to help absorb moisture that will accumulate In the tank during storage... I've had one customer that did this excessively and the alcohol content eventually became too much for the engine to manage and burn on its own.
If you do need to drive the machine every couple/few weeks, it shouldn't be an issue. keep the fuel tank topped off on every other drive, and forget additives unless you know it wont be used for a long period of time. Gasoline does degrade, but from your use case it sounds like that shouldn't be too much of an issue.
More importantly if, during the times you *are* driving it, as long as the car gets to operating temperature and it gets some small amount of highway driving it should be A-OK! Otherwise, keep It stored. I've seen engines that slowly accumulate moisture from short drive cycles that they are effectively 20%ish water in their engine blood, no good.