ben said:re parking - not sure of the name of it, but there's an NCP (i think) by the canal - behind the tesco metro / sainsburys fast thing - thats about £5 for 24 hours. Secure + lit.
Also, cheaper (well free) are the streets behind broad street - William Street and Holliday street (again, i think) - but def that general area...
not sure about the William street but Holiday street has parking early on in the night