just go drop it off....go have a coffee, dinner and pick it up later on in the day.
By time you spend £30 on a flash cable, thats already 10% of the way towards a proper remap.
Only way I would say have a go yourself is if you know what your doing and prepared to take the risk. trust me, its not as easy as it looks when starting out....I can assure you that. I must have made 40+ changes to my files and im only just starting to get the car to boost where i want it.