Ah, more misinformation. No, PRS do not "own copyright" in anything". No, you are not contracted to them. No, you are not donating money to the owners of the Beatles publishing.

PRS deals with live concerts. Venues have to pay a PRS license fee (quite rightly), and the writers of the songs performed at that venue get paid. You can register setlists online now so there isn't really an excuse for grumbling that your money just goes into the pockets of the "big guys". If you fill in the form, you get paid... easy.

For website streaming it is MCPS, not PRS, you need to talk to. If you are streaming your own songs, and you own them (i.e. haven't signed a publishing deal or assigned the rights to anyone else) then you don't need a license. You would only need one if you were offering other peoples songs.