Thomas Cook tried this with us 2 years ago. Swapped our Glasgow flight to Newcastle, with no offer of a reduction, or paying our fares to Newcastle. It was take it or leave it. So we left it and took our full refund.Managed to get other flights, but it put our holiday dates out by 2 days, which is ok if your work is flexible.
This years fares are shocking. We are going in June from Glasgow to Bourgas at £260 each. We want to go back in August, but Glasgow flights are all well over £300.Tried Edinburgh, and got a better deal with First Choice, but its not exactly a bargain.