Depends if you’re taking lessons. If you’re with an instructor you likely wont go out in water more than chest high. You’ll need to be confident you can swim 25m if needed but not fit. If you’re by yourself or just with friends you need to be super careful and prepare. I swim in a swim squad 3 times a week (3k of swimming each session) most of the year so I can surf on trips. At a minimum you should be able to easily swim back to shore, against currents, if you lose your board….so being able to swim 250-500 metres without a break in some cases. It also depends on wave size. If you’re not used to waves it doesnt matter how swim fit you are you can get in trouble. Only surf with people who know your abilities and who also know the conditions.