I'm confused how many of my training long runs/miles I should run at race pace in the lead up to a marathon. I mostly train at about +30 sec pace on long runs. But I'm aware in the weeks leading up to the taper it's important to log some miles at race pace.

You have made a great start by training at +30 second race pace in your long runs. As you have suggested, running some of your long runs at race pace can be beneficial, but you need to be careful that you don’t burn yourself out ahead of the race.

The most important skill to develop on your long runs is keeping your pace consistent. If you are running your first mile at +30 second race pace, then you should still be able to run at this pace by the last mile.

If you haven’t mastered this yet, then don’t worry about training at race pace yet. If you do feel confident in running a couple of long runs at race pace, be disciplined in these sessions and keep a close eye on your watch. With enough practice your body will naturally adapt to this pace, and on race day it will seem second nature.

However it’s unlikely that you’ll do the full marathon distance in training so don’t worry overly about this. You’ll find that the last part of the race will be much tougher on your body and you’ll settle into whatever pace you need to get you through.

It’s also important that you don’t get carried away with the excitement of the event and set off too fast. This is a common mistake, especially with first time marathoners and one that can have a significant impact on your overall time. This is difficult to replicate in training so just bear it in mind.