(Reuters) - UK shares inched lower on Tuesday, as worries over protests in Hong Kong, the U.S.-China trade spat and the health of the British economy continued to fuel a risk-off sentiment, even though travel firm TUI rose after quarterly results.The main index edged 0.1% lower as it fell for the third straight session. The mid-cap FTSE 250 gave up 0.2% by 0715 GMT, though online trading platform Plus500 soared 10% after half-year results.London-listed shares of tour operator TUI advanced..