The two groups that come to mind in terms of costumed participation at comic events are the U.K. Ghostbusters, who have attended the SFX weekend at the London Movieum and we did a walkabout in London the weekend after the game was released. From this group, Mark Lloyd and Carl Hopcraft and myself (Ben King) post online the most frequently, unfortunately both Mark and Carl don't post on this site. More of the team post on the U.K. Ghostbusters forum which is accessed via the site.
Another group, the GBUK Elite have attended Collectormania Milton Keynes. Out of the four members, Andy Grey, Lawrence Juniper and James Mann post the most frquently, however again the majority of this occurs on GBFans.
Both groups have attended (in various numbers) the MCM Expo at the ExCeL Centre and the London Film & Comic Con at Earl's Court for the past number of years, often to much positive reaction from the public, as we've experienced at the other events/outings we've been on.
On the U.K. Ghostbusters site there aren't any members listed in the greater Manchester area, however there may be some who aren't on the featured members page, or some who haven't signed up yet.
You can find out more here:
The U.K. Ghostbusters - Official WebsiteGBUK: ELITE - Official website Some may be willing to make the trip out there, but that's subject to financial constraints.