General information for visitors to Warwick University can be found here: https://warwick.ac.uk/about/visiting/
The best railway station is probably Coventry - from there you can take a taxi to campus (~£12-15 each way) or take the number 12X (~20 minute) or 11 (~30 minute) bus. The buses require exact change or will accept any contactless payment card (approx cost: £2.40 one way, £4 day ticket).
As with any other university, car parking on campus is a chronic problem and you should read the university page on parking (https://warwick.ac.uk/about/visiting/directions/car/parking/) and expect to spend time hunting for a space if you opt to drive.
The meeting, coffee and talks can be found in room MS.04 in the Zeeman Building.
The pedestrian route from the Warwick Uni Bus Interchange to the Zeeman building is marked in red.
Lunch and the workshop on 19th September will be in room PS0.17a in the Physical Sciences Building (adjacent to Physics). The blue line indicates the best pedestrian route from the Zeeman building to Physical Sciences.