You may not like this advice but here goes: Go to the race and watch the 3 events to get some idea what's going on. Talk with other cat 5 racers and learn as much as you can. You currently don't have the fitness to race competitively and will get spit out the back (dropped) in short order in the RR and crit.
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"You never fail, you simply produce results. Learn from these" - Anonymous