You can check out LINX out of the UK. Its is a decent public exchange point out of the UK and currently has the most participants out of all other peering points in the UK.
You could also try
www.peeringdb.com -- a great resource for peering data from a global standpoint.
Hope that helps...
Pablo
I am doing some work on a network in central Illinois that is
currently peering with Sprint and McLeod. They have a number of
customers in the U.K. and they want to reduce latency to that part of
the world. They've been offered a point to point 100 mbit link between
their facility and a location in London from Cogent, but this isn't IP
service. They've asked me to sort out how they can use this link or to
find a good alternative for them.
A long time ago I think Teleglobe peering would have been the snap
answer for European connectivity, but its been a few years. Who would I
look to in terms of a carrier on that side of the pond? We've got on net
termination with Sprint as a starting point for a link ...