Ooof! £750.00
There's no way I'd pay that on a 3 year old car, you'd probably find the Warranty doesn't cover you for major items like the clutch etc anyway.
I'd say treat the car with care, increase the amount of oil changes going forward and plan your own maintenance schedule to iron out problems before they arise.
I've had my 2005 car from when it was just under 4 years old and I've never had an unexpected failure that would've had me phoning the warranty company.
I'd say the only time a warranty is worth it is during those first few months of ownership where you inherit the previous owners issues, then if you're lucky the car dealer will cover the repair but buying a warranty on a car you already own just seems a waste.