If you live in Leicester then HS2 is no use whatsoever heading to London, considering it will take you 25 mins to get to the East Midlands Hub station, then 50 minutes on HS2 to London. Its just over an hour now anyway to St Pancras. Could be useful heading north though, although electrifying the existing line could be a better and cheaper way of doing things. Either way, the 2nd leg of HS2 is probably 20 years away from opening.
Another thing is people ask why spend £100B on a new railway line to increase journey times between London and Birmingham. The major reason HS2 is needed is to increase capacity, the faster travel time is just a bonus. At the moment the west coast mainline from London to Birmingham via places like Milton Keynes, Northampton is maxed out. Long distance trains, commuter services and freight all squeezing onto one line. The line was upgraded maybe 20 years ago for the Virgin tilting trains and its already struggling to cope.