Micky, could be worth you checking out BAS (britains aquatic superstore) in Bolton, I know it's not North East but they have some gorgeous plecs in at the moment. Could be worth you making a day trip! They do have a website but the stock list is not upto date, I'd ring before travelling.
May be worth trying Aquahome in Leyland as they have some very nice fish, including plecs. The staff are also very helpful and knowledgeable, the tanks are clean and the fish are healthy.