Re: Are you interrupting attacks?
We do early entry against the striking arm, where I agree with Cliff, it hasn't really got moving yet so there's no clash, this tends to be the entry for tenchi, the immibilisations, tantodori, etc. When it's done really well just the entry will throw uke. We also corner step and blend with an indicated irimi to the face, for shihonage, iriminage, etc. - sounds like what Billy described.
At summer school we also did a very direct entry coming inside the attacking arm to nullify it and bringing tekatana mentsuki in at the eyes, taking them right back over their heels. I landed awkwardly on my shoulder during that one, not especially easy ukemi first time out.