Wildlife Garden Stage 2 - rock pile

(even though the greenhouse isn't actually completely down yet lol)

I have a logpile, now as there are concrete blocks that aren't going to be removed, I'd like a mossy rock pile!  We have a few mossy rocks in the garden but I think all of these are currently in use so I'll have to start from scratch but I wouldn't have thought it  would take too long as there is a lot of moss in our garden.  But just in case, is there anything I need to do to speed up the mossing process?  And are there any Britrish plants that stick to rocks?  I know bromeliads grow on rocks but they aren't anywhere near native and I'm pretty sure none of them could survive in the Scottish climate anyway so I was wondering if there were any British plants that would work?  The rock pile will be about 2 foot by 1 foot (and there is two of them as there are two concrete blocks).  Since I don't think there is much that can be done with the concrete blocks and it would take a big drill to get them out they will be staying.  Alternatively, does anyone have any other suggestions on what can be done with the great big concrete blocks?  Does moss grow on any rocks or are some better than others?  I have lots of moss in the bottom of the garden, could I just transplqant some of this onto the rocks to speed things up?  And does anyone think I am mad trying to "grow" moss??? lol