Cracking lawn that mate.. Do you water it regularly?
I've been there with the piss patches... got the t-shirt and all that!
I found a good tip, when patching up piss stains, is to mix the seed with some soil in a bucket and wait until it's germinated before putting on it on the lawn.
Gives you almost instant grass and you won't have the birds hammering the seed as they would do if you you put the seed directly onto the lawn.
Just keep the soil in the bucket moist and give it a little shake around every day or two.
I wait until the shoots are about 10 mm long before i