bt, I did my Oly yesterday under similar circumstances - not the training I had planned months ago when I signed up... it was to be my A race but my training was more like a C race at times...

I say to go for it if you can. I didn't have a great time (result) but I had a great time (experience)! I think it was worth knowing/learning about the distance and I got the same medal and shirt everyone else did.

I will have more on the race later but hope you are coming to resolution. I think if you allow yourself to adjust the goals you may have set then you can still get a lot out of it.