They will have to do a lot more than the normal syllabus to get the degree. The syllabus will give you credits within the degree. But not the full lot. There will also be a dissertation to do.
Hence modular wouldn't cut the mustard unless they got the Open university involved to make up the rest of the syllabus. And none of the big players will be pushing for that.
And the university won't matriculate you for nothing there will be additional fee's for the degree side of things. It doesn't matter if you are on campus or not. And on top of that you will have to pay for the flying side of things.
The good news is though that they may be able to not charge VAT on the course because of the education degree side of things. But I suspect the customs and exercise may have something to say about that as it will mean they will be 12k down on each student. Or of course they may charge you the standard price and pocket the VAT as profit. I have a suspicion I know what they are going to do if they can get away with it.