Circled in red are 1) the Church and 2) the Assembly Rooms. You must go to them in that order. The Church is a 2 minute walk from the Assembly Rooms.
This is all walking distance from Bath Spa railway station, where you can get trains to/from London Paddington, Bristol and Didcot Parkway. Give yourself a bit of time if coming by train; they are as reliable as official statistics from the Chinese government.
There are several hotels around the centre of Bath (see 'Accommodation' for more details), all within a couple of minutes' walk of the venues, so you can fall out of the Assembly Rooms and stumble to bed without a taxi.
Parking in the city centre is expensive but possible if you're patient. If your hotel offers parking, take up that offer if you can. Otherwise, there is a big car park on Charlotte Street and Avon Street, but occasionally tourists stand in the spaces to reserve them. Bring weapons.
There's also the Park & Ride in Lansdown, if you want the difficulty of parking as well as the horror of going on a bus.