Brilliant info from DG, Imagine. The other cost that will be incurred, unless you have a chum in the business who'll do it free, is the haulage of your furniture, etc., to the new home. A small local removals business might be fine, but do make sure they're fully insured against all damage or loss of your stuff. It depends on the length of the trip as to how much it'll cost you, because that determines how much time the removal men will be working, and that's also on how much you'll be giving them to take. Good idea to start chucking out everything you don't like/don't use, to reduce such costs. You can usually get a rough, over-the-phone estimate based on average house sizes, etc. to give you an idea to start with. Try three or four soon, so that's one estimated cost you can jot down.
And, at the risk of teaching Granny to suck eggs, don't forget that once you have a definite exchange of contracts and your house belongs to the new buyer, to stop all of your utility bills' payments from that date. Phone, broadband, tv services, gas, electric, water, Council Tax - instruct your bank to stop all of the Standing Orders or Direct Debits you have concerning the property. Make sure that formal final readings of gas, electricity and water use are made just beforehand, so there's no quibbling.
Good luck!