There is no partial refund of a ticket that you have accepted to rebook (because you didn't decide to cancel the ticket, fully or partly). There is no compensation under the current EU Reg. 261/04 for incidentalt costs incurred or inconvenience due to a cancellation. The regulation operates with fixed amounts as comp. for cancellation of a flight, however, this far out (> 14 days) there is no right to compensation. Hence, any req. for compensation is likely to be denied.