Descent magazine has published annual summaries for about 20 years with a short narrative for each call out.
The summaries include all mine exploration call outs. Caving call outs predominate by a considerable margin - but we have only a very approximate idea of the size of the UK caving community, and even less of a numerical grasp of the size of the UK mine exploration community, so it would be extremely problematic to attempt a calculation of relative accident rates of mine exploration versus caving.
For what it's worth, I'm of the opinion that in relation to number of trips or number of hours underground, mine exploration results in fewer accidents than caving. This is based on 30-odd years of going underground, roughly 50:50 mining to caving, the mining (mostly lead) including a good deal of pushing in little-trodden areas and digging.