Shock, horror!
My HUDL told me last night there was an update waiting, I thought it would just be a minor one, but it turns out it's the 5.1 update. Installed OK, took a while but that's to be expected.
This morning has not been so good. 2 crashes, problems connecting to The Cloud wifi, space issues and general slowness. I'm doing a factory reset, so we'll so how it turns out after that.