Sprint or Oly before 70.3?

I'm doing my first triathlon in August and signed up to a 70.3 (Cleveland Steelman, UK). Looking to maybe do a sprint or olympic (Ripon) first for experience but wondering if it's needed or worth it? The date I'm looking at is 3 weeks before the 70.3 so not sure if that is too soon before? Also whether I would be better doing sprint or olympic? I feel like I'm forking out loads on race entries at the minute as I just signed up for a marathon next year and a sportive in the lead up to the tri. The prices are £75 or £90.