I have an abscess in the roof of my mouth next to my rear molars, is it likely i will have to have the tooth out, even if the abscess clears?

Possibly, but it: Needs to be evaluated by your dentist. You may need a root canal, you may need an extraction, there may be different options.

Needs evaluation: Many teeth are restorable, some are not. Your dentist will have to discuss your options with you.

Palatal Abscess: There is no way to know without personally evaluating the cause of the infection as well as the condition of the teeth and the supporting bone. The sooner you see a dentist, the better the chance of saving the tooth or teeth and preventing the spread of the infection which will cause you even more problems.

Clears?: Abscesses don't clear. You have an infection that will only worsen and spread to other organ systems. Please seek treatment now. The tooth may be salvageable with root canal treatment/crown or replaceable with extraction/implant crown. See a Dentist ASAP.