This scheme was started by Jason Johnston W3AAX following the completion of the one organised by the ARRL with the target of activating as many as possible National Parks in the USA, during a year. So many Radio Amateurs became involved that following the year there was a high level of interest in working from National Parks. As a result, Parks on the Air was born.
In some ways POTA has a structure similar to SOTA (summits on the Air), but with parks generally being a lot more accessible. In the Parks on the Air (POTA) scheme you can even work from a parked motor vehicle.
POTAs main website is at https://parksontheair.com/ everything you might expect is there, except spots and alerts which are at pota.us. The scheme is expanding outside of the US currently however there is very little information on what is happening from the point of view of England. It is expected that this will be resolved by Andy 2E0UAW who is the Administrator for England. Scotland, Wales, Northern Ireland etc. are separate and so there are a few open Job opportunities.
As with SOTA you have activators and chasers (hunters in POTA terms), you are required to make at least 10 QSOs during an activation in any mode you like however as you would expect, you can not use a land based repeater. The same as in SOTA however you can make contacts via a satellite (this could be useful if your park is located down in a valley).
You can’t just operate any old park - it has to be on the POTA database, and this in England mainly applies to National Parks, Country Parks, and Areas of Outstanding Natural Beauty (AONB) like the Lincolnshire Wolds for example.
Parks on the Air England - https://stats.parksontheair.com/reports/park-info-select.php?entity=England