The UK's currency is the pound sterling (£ / GBP).
There are 100 pence (p) to the pound (£). Notes come in denominations of £5, £10, £20 and £50. Coins come in 1p, 2p, 5p, 10p, 20p, 50p, £1 and £2.
Exchange rates: http://www.xe.com/currency/gbp-british-pound
Check if you need a VISA: https://www.gov.uk/check-uk-visa
UNO runs local buses throughout Hertfordshire and into North London, and fast, direct links to and from the University of Hertfordshire: http://www.unobus.info/
Coach and Bus Travel - National Express: http://www.nationalexpress.com
Hatfield train station: http://www.nationalrail.co.uk/stations_destinations/HAT.aspx