Ball park figure would be �1500 to �2000. There's lots of options even with cremation, caskets can go from �100's to �1000's.
Then there's the church to pay for( or maybe have it at the crem itself), minister, and finally funeral director's fee.
Think the Co-op still do payment plans, so you can either pay it all now or pay bit by bit. Or go and chat to one of your local funeral directors.
http://www.co-operativefuneralcare.co.uk/
There's always the green option too.
http://www.funeralsearch.co.uk/woodlands.php