It really depends on the life the clutch has had up till now. If it's had a hard life it may start to slip as soon as the remap is on the car. If it's been treated well you might get another 20 - 30k out of it. Either way it's best to budget for a new clutch in my honest opinion at that sort of mileage. No need for anything fancy just a genuine standard replacement from vw or tps (unless you plan to go further with the tuning, hybrid turbo etc.).
If you're not heavy with the right foot all the time then mpg increases are usually seen.. but that can be hindered by boost leaks, failing coolant temp sensors, maf sensors and clogged up EGR valves so that's the sort of stuff i check over before the remap. I can investigate the airbag light at the same time.
I'll drop you a pm about making a booking
