The answer you don't want to hear is: yes, you probably do. While permitted development and repairs may not need planning permission, that doesn't exempt you from your obligation under various laws that protect bats and their roosts from disturbance or harm.
It rather depends on the state of your roof. Naturally, re-roofing is something that you'd expect to do if the roof is in poor condition, so ultimately, it is likely that you will need a bat survey to either give you the 'all clear' or advise on how to mitigate for harm, killing or disturbing animals.