A pressure washer will definitely save a lot of time, but the loose ridge capping would make me avoid using full pressure straight away. Around 2,000 PSI is usually enough for moss if you keep the nozzle at a reasonable distance and always work from the ridge down toward the gutters. That helps reduce the chance of forcing water under the tiles.

Another option is to remove the heavier moss first, then apply a roof-safe treatment to kill the remaining spores before giving it a light rinse. That approach is often easier on older tile roofs.

If the capping is already loose, it may be worth having those sections repaired before washing. A local roofing company can usually assess whether the roof is safe to clean first or if a few repairs should be done beforehand. Spending a little time on that step can help avoid water getting into the roof space or causing extra damage. After clearing back those cypress trees, you’ll probably find the moss comes back much more slowly because the roof will dry out faster.