Yes you can fly IFR in class D airspace but you don't need to file a flight plan on the ground just for this, it can be done in the air by radio prior to entering class D airspace. However if you are flying over mountainous terrain or the sea then it is a good idea for SAR purposes. I think you file your plan with Manchester in your case. Hope this helps. <a href="http://www.ais.org.uk" target="_blank">www.ais.org.uk</a> gives full information if you need anymore