If you are mainly going to be printing black and white then go for a laser printer.
Dabs.com (click here) have a Samsung ML1210 for £99 inc VAT. It has either a USB or Parallel interface.
Ebuyer (click here) have a Samsung ML4500 for 65.38 inc VAT. It only has a Parallel interface though. (I have one of these and they are very good value for money.)
If you go for any of the laser printers above, you'll have enough money left to buy a colour inkjet printer for when you need to print in colour:-
Ebuyer (click here) have an HP Deskjet 3820 for £63.14 inc VAT. It only has a USB interface. (My girlfriend has one of these and they are a nice neat unit with good print quality).
Total price for the Samsung ML1210 and HP Deskjet 3820 from Dabs.com is £168.32 inc VAT and Delivery.
Total price for the Samsung ML1210 and HP Deskjet 3820 from Ebuyer is £167.61 inc VAT and Delivery.