In addition to GANFYDs points.
Yes, I seem to remember reading on here at one point (a year or two ago) that if you were non contextual you had to have full GCSEs and top UCAT, because the contextual points leapfrogged over the top to a great extent. I think they have adjusted their weighting slightly since then which has reduced this effect.
Look at the published interim deciles and score yourself for that decile and the one below. Are you comfortable applying with both ? How comfortably are you in that decile.
NB, yes, I know the final deciles will likely be lower, but the birm deciles are gen slightly higher than the UCAT deciles, so interim is a possible proxy.
At the end of the day, it is a risk, but so is everywhere because you don't know who you will be upagainst in terms of applicants. All you can do is make logical and strategic choices on the basis of the info you have.
Good luck.