Traditionally: a noble house charges for the use of gatestones, which act as a portal for the masses. Some wizards such as myself can open a gate without a gatestone - it’s tricky magic - but it’s also illegal magic, given what I’ve indicated about the noble house having the monopoly on gatestones.
To travel to the Lighthouse (pocket dimension) though... you just have to know the thin spots. Anyone, magically inclined or no, can access it once they understand where they may enter from.