UCL has a strong brand name and is well known to employers but perhaps more importantly, their Project Management for Construction degree is based at The Bartlett (a very prestigious school of architecture, urban studies, planning and construction). Prestige isn't everything, but it's something to consider.
I would be very surprised if Loughborough had better employment links than UCL, why don't you contact the department and ask about career prospects/which employers visit the dept each year looking for graduates? Or better yet, visit and get a feel for the campus.