The main train station in Bath called "Bath Spa railway station",it located in the city centre and next to the bus station.You can purchase ticket onlinehttps://www.thetrainline.com/(if you have a UK address to receive it) or at any train stations in the UK.
Outside train station you can always find taxis, local buses just about 2 mins walk away, bus stop is located in front of Bus station on Dorchester St.
Bus station is located in the city centre as well, it has National Express, also local bus stops just in the front of the main station on Dorchester St, you can pay cash on the bus(local bus only),or buy a pass through their website or app.
Local bus service----https://www.firstgroup.com/bristol-bath-and-west
Price(Bath inner zone): Single ride---£2.5 per person(adult) £1.8 for people age between 16-21years old and full time student(ID required)
£1.3 for people age between 5-15years old
Day Pass--- £4 per person(adult) £3 for people age between 16-21years old and full time student(ID required) £2 for people age between 5-15years old
Online booking available, you can also purchase the ticket at bus station
Price may vary depends on your purchase date and departure time.If you book early and avoid peak time than the price will be cheaper.
3.Airport Shuttle Bus
The nearest airport is Bristol Airport, and you can take a airport shuttle bus from Bristol Airport to Bath city centre. Ticket is available online----https://www.airdecker.com/book-ticket/ Check timetable here
Price: Single:£14 per person (adult) Return:£20 per person (adult)
There are some public rental bike around Bath centre,they called "Next Bike'.You can find them next to the train station and Green Park, or go on their website or App to find more details--http://www.nextbike.co.uk/en/bath/
First 30 mins per ride----£1
Every additional 30 mins per ride---£1
Register &Payment method: Register once via Terminal, App, hotline (+44 (0)20 816 69851)
Payment by Credit Card or Direct Debit