So many people have to deal with leaking roofs day in day out and often we put the repairs off until it becomes so bad, we have no other option. It may be that your roof only leaks during serve weather or when the rain is blowing in a certain direction.
Delaying repairs may mean that it ends up costing you more as more damage has been done or the repair is now irreparable.
When it comes to leaks on older roofs you do need to think carefully as to if it is worth repairing the roof or whether you are better to replace it. Replacing a roof will cost more but you often get a guarantee with it so if you find you are having to repair the roof more often then over time the cots of replacing it will probably work out financially better.
If your roof contains asbestos then you will need to factor this in to the cost as removing the roof will cost more as it requires specialist equipment and people who are trained to be able to do the job correctly.
Do not be tempted to skimp on the price of a roof as you may end up paying for it down the line.