That workout would be reasonable later in the season if you were planning on sprinting or racing but since you're not I would recommend basic threshold intervals instead. Here's an alternative:
10 min warmup
5 min @ FTP (threshold power)
5 min easy
20 min @ 90-100% FTP
5 min easy
20 min @90 -100%
10 min cooldown

Do these 2-3 times/week and you should move up to the A-ride.

If you have a trainer with published speed-power curves you can determine your FTP by measuring the highest speed you can maintain during a 20 min all out interval. Your FTP would be approx 95% of your 20 min power.