Just to update this. Thanks for the advice folks.
Got the seats and seals done over the last week. Was a bit of a pain finding a 20mm hex so I managed to grind down a 21mm wheel bolt to fit.
New seats in and not leaking yet. Fixed 2 vac leaks to whilst was there, new NGK's and the motor is much happier now.
Scanned for codes and was clear which was brill as I was antipcating a fault code to come my way.
Thanks