We had a similar problem where a chimney pot was removed and some tiles replaced and the estimate came to �250. Luckily we got it done by a friend who only charged �70. The work was completed within 2 hours.
Don`t know the age of your property, but if its pretty old you might has well safe yourself a load of hassle and put a flue liner and the appropriate cowls
We had the same issue with the house we moved into last year - we had the chimney uncapped and a new top put on, including a "cage" top (don't know the proper word for that type of cowl) to stop birds coming down the chimney. Our chimney sweep charged �65 for this, which I felt was reasonable. We're now able to use our fireplace, which is great. If you've got an older property and there's no record that the chimney is ok then you will probably need to have it properly checked. Your local chimney sweep ought to be able to do that and give you a quote.
I would strongly recommend haviong a fitting on the top which prevents birds coming down the chimney - I've had experience in a previous house of birds down the chimney and it isn't pleasant!
thankyou all so much,the quotes I have been given seem ridiculous to me,if I wasnt afraid of heights I would try to do it myself:).The quotes I got were from roofers,tomorrow I will try sweeps for quotes,I didnt even think of that,thankyou Growbag.I will put a bird basket on top too as seagulls nest on the roof in the season.
Hopefully I will have a beautiful working fire in time for santa.Merry Christmas everyone