A) It depends on what type of legal animal you use. A solicitor is more expensive than a licenced conveyancer, who is generally more expensive than a bucket-shop solicitor. These can be found by searching the web.
No, you won't incur CGT on any profit you made provided it has been your principle private residence.
B) See answer to A) above - impossible to guess.
On Monday morning, search your Yellow Pages for a few legal companies, phone and ask for a quote. They are very used to receiving such calls and will quote you over the phone based on your transaction values of sale and purchase. You will be surprised how similar all the solicitors are in price. Some people believe it might be if the Law Society issues them all with suggested price lists to work from, but that can't possibly be right as that could be construed as operating a cartel.