I did the PGDL online at BPP. I thought the course itself was good - it was thorough and delivered well. The content is online reading (quite a lot of it), some prepatory tasks in a commercial context, and a seminar per week per module. The quality of the seminar will depend on your group, as some people login to the sessions for attendance and then either refuse to participate or maybe aren't even there at all. You'll get far more out if you participate so I'd recommend just learning to live with any awkwardness.
Some people were very unhappy with a lack of printed materials. I personally didn't mind, but I prefer my notes being electronic so it's very much personal preference. Assessments were, with some limited exceptions, a combination of multiple choice with a best possible answer, and a written section. All are open book and not proctored. Having organised notes is a must, and I'd suggest doing that as you go, rather than trying to consolidate everything at the end of each term. The open book nature can be a little deceptive - the word limit and time limit on the exams will definitely catch up with you.
The assessment for human rights and administrative law (Public Law 2) is an essay. Criminal law has an oral component that is a recorded video. Trusts and Land have a combined written component but separate multiple choice elements.
Some of the online resources were patchy, in that the law would be actually incorrect. This was amended over time and seems to have been issue with our cohort as the first to do their new PGDL a few years ago. They were pretty isolated and I would assume they've been fixed.
I can't comment on how they combare to ULaw so hopefully someone who has done the PGDL/MA there can chime in.