There is no general exclusion from travelling abroad whilst serving a community order.
However, travel abroad may, in practice, not be feasible due to the requirements of the community order, e.g. a curfew, regular unpaid work or supervision. If you require a variation to these requirements in order to travel abroad (for example, rearranging a meeting) then you will need to seek permission from Probation.
There may also be a specific prohibition as part of the community order that stops you from travelling abroad. If you are in doubt, you should contact your offender manager.