RHUL is a college of London University. The degree it would aware would be a London University degree. Both the college and the london degree are well regarded. (London University is federal. All its degrees are taught for and awarded by member colleges. The fact that the college awards the university degree rather than its own qualification does not mean the college is second rate. Some world class institutions are "only" colleges of London University.)

I think you were looking at the cost of studying in the flesh though, this page http://www.londonexternal.ac.uk/pros.../ug_cost.shtml suggests it would be quite a bit cheaper, though still not cheap. And its not that clear.