If riding north on the east coast to Ulster you could nip up to Kilkeel to Newcastle to Strangford and over on a short (20min +/-)ferry crossing to Portaferry along the coast road to Newtownards to Belfast(avoid West Belfast as it's a shithole)...on along through Carrickfergus(where you'll see an excellent example of a Norman Castle)
On along the Antrim Coast coast road is not too bad a ride where you can glance over and see Scotland...ride on up to Portrush via The Giants Causeway via Dunluce Castle and head on along towards Donegal etc.
Westport has some great wee pubs and even scoot on over to Achill Island in County Mayo.
You should get a large 'pub grub' meal costing about -£10 in most town pubs.
You'll miss the NW200 (in May..pre races as it were to the Isle of Man TT races) but if you're interested,i.e. in Road Racing you'll get dates here
If you're interested in WW2 stuff have a peep here