Unfortunately, you haven't told us where you are in the UK, so I don't know how cold your winter was likely to have been, but in the south, most tree ferns should by now be showing buds, although they do seem to be a bit later this year, along with lots of other plants. without knowing where you are, it's hard to comment, but suggest you give it more time - should be growth by end of April at the latest.

I would release it from the bubble wrap unless harsh conditions return. B'wrap, is after all, plastic and you don't want it to rot underneath it all.