You can use ecalyptus to help drain it along with willow and dogwood (cornus) will survive being flooded too. Pears and mulberry enjoy wet but not waterlogged soil so you might be able to include them in a drier patch or on a mound somewhere. If you can incoorperate as much carbon into the soil as possible especially (with using biochar) it will help with it's water holding capacity long term helping to buffer some of that wet into the drier months.

Being in Ireland though I hope it's not a literal bog that might be challenging!