I've never been the fastest of riders (not really been one of my aims) but I'm now going out with a group who ride at a faster pace than I have previously.

Is there anything I can do to get my body used to riding at a higher pace or will it just come through trying over time?

Fartlek

You won't get faster by trying to ride up to it. So going out and just trying to ride faster won't really work.

Intervals is where it's at. Two types. Try these on a Tuesday and a Thursday.

1. Short intervals. Remain seated and accelerate hard right up to maximum speed, hold it for 20 pedal turns then relax. Wait until you get your breath back then go again. Do as many as you can before the quality goes.

2. Two to three minute intervals. Accelerate hard, and hold the fastest pace you can for two to three minutes. This pace will be faster than you can maintain for any longer. Put a couple of markers down. After you've warmed up, do your interval. When it gets to the point that you're "off the mark" of your second interval you're cooked. Warm down.

If either or the above become to easy, adjust the length/duration.

HTH
SB

Been one or more threads on this lately.

Intervals FTW, though you will get faster (not as quickly) by trying harder on rides.