I was thinking that too!
In terms of location - the Peak district is fairly central, has some great trails and there is already one HP there (SkyGods). Salisbury Plain could be also be good not least because there are some big open trails well suited to be blasting on the HP...
In terms of date - there are a whole bunch of holiday weekends around the end of April and early May (Easter, Royal Wedding and May Day). What about one of those weekends?