The conference will be held in the Maths and Statistics Building (abbreviated 'MS') on the main Warwick campus. Note that Warwick is on the outskirts of Coventry (not in the town of Warwick). The Coventry train station is about 15 minutes by taxi (around £10 each way), and about 25 minutes by bus (at the moment £2 one way, £3.90 for a Daysaver ticket that will take you both ways). You should look for the National Express Coventry 11 and 12 buses, which stop a few minutes' walk from the train station (follow signs to Warwick Road) and drop you off a few minutes away from the MS building (and the 11 and 12 buses do not provide change). The campus bus stop is on University Road just past the intersection with Library Road. The train station in Leamington Spa is also fairly convenient for getting to campus, with the 11 and 12 buses, as well as Stagecoach U1 buses, following routes to campus that go near the Leamington station.
Here is a link to the university's information on visiting campus.
The number 15 and number 8 carparks listed on the campus map are both very close to the MS building. It costs £1.50 to park for up to 4 hours, and £3.00 for the whole day (these are pay and display, and you will need change for the machines). The 15 carpark is the first one you will come to, and it is larger, so it probably makes sense to try that one first. The workshop is being held outside of term, so it is unlikely that it will be difficult to find a space.
One further note: the campus is undergoing construction and roadworks, and the traffic patterns have been a bit unpredictable. If anything too awkward is going on that day, we will try to let you know.