Are these fossils?

Sort of, they are sedimentary structures caused by scouring and then infilling of sediment, often during submarine sediment flows.

YAAAAAAAAAWNn

Would they have been formed in the streamway of a cave or on the surface?

Most probably a submarine debris flow, almost like an avalanche of sediment flowing down an offshore slope into deeper water. In doing so, it scours the underlying sediment and those scours are infilled and retained here - This is the base of one of those flows.

If you're not interested in something it doesn't make you clever, Will.

A bit of context, Rog. I'm studying Physical Geography at Leeds Uni where Dave is doing Geology. Bit of inter-course rivalry. I do find this stuff interesting but unfortunately its not my field so I don't know enough to fully understand the process which Dave is describing.
Maybe I'll ask you at the Packhorse on Wednesday Dave? Maybe I'll fall asleep in my pint?

You'll be hard pushed to find me at the Packhorse these days Will...

Even I understand this Will and I was crap at geology 3 years ago. I thought you knew all about castes anyway?