Hot? yes, but apparently cooler than England right now as long as you're a meter below ground in a ring around the poles (how's a constant 21c/70f sound)
this guy's website is so weird but I love the novelty of the idea and he portrays a plausible scenario for it being ultimately more habitable than Mars
Mercury orbits at 48 km/s and Earth orbits at 30 km/s for anyone else who was wondering about this.
Edit: Actually this doesn't tell the whole story...
So yeah you need to go faster to get there, but you'll be going way too fast if you don't spend a bunch of time doing break checks around venus and mercury before getting there