Perhaps someone could explain what, exactly, China's defence expenditure has to do with the UK?
They're a long way away, and anything we could deploy at that distance would look pretty pathetic in a PRC/NK vs US/Japan/SK/Singapore/Aus/Taiwan scenario. The risks of our getting involved would vastly outweigh any benefits we could gain by having a miniscule effect on the final outcome.
When 2 giants start squaring up to each other, it behooves pygmies like the UK to get the **** out of their way.