Golf gt tdi 2.0 140 bhp mk 5 - esp light

When there's something wrong with the brake pressure that handbrake warning light comes on.

The ESP warning light could be caused by a lot of things, but most likely it's a dirty fuel filter. Don't take my word for it though, just go to the VW dealer and have it read the faultcodes from the ECU, which should point you/them in the right direction.

Alternatively, when you have the right equipment (= VAGCOM + cable) and knowledge, you or a friend yould diagnose the ECU yourself.

From the sounds of it, you'll need a small service (air filter and oil filter change, etc.) anyways. Don't forget to reset the ECU (or dis- and reconnect the battery) afterwards to erase the faultcode from memory (when there's still something wrong, it'll return soon enough).

You might get lucky with a small service :)