I am an experienced CP / CBT / medical sub based in London.
I have served both male and female Dominants in the past, so am very comfortable with any Enforced Bi play. My anal hole is well trained, but my deepthroating skills are still being worked on. I have experience with A2M (covered only), and am also happy to rim and/or swallow.
My main experience is with CBT, focusing in particular on ball beating / busting (up to quite severe), ball crushing, and cock beating (up to belt / cane). I also enjoy sounding, catheters, stinging nettles (including insertion of nettles into the urethra - as well as anywhere else) and electro on my cock and balls.
I also have experience with a wide variety of CP implements (crop, paddle, bath brush, cane, flogger, tawse, belt, ruler, strap, whip, ...), though my pain threshold for CP is slightly lower than that for CBT. If you expect to leave any longer-lasting marks, it would be good if these could be restricted to the area covered by t-shirt + shorts, though this can be discussed if you have other requirements. I particularly enjoy CP to my anus (crop / cane / thin flogger), and this can really make any complementary anal training a lot more memorable.
Medical experience includes catheters, urethral sounds, bladder inflation, speculum play, prostate milking, fucking machines, electro play, ruined orgasms, post-orgasm torture (glans polishing etc.) and punishment enemas. I am very open-minded if there is anything else that you would like to try.
Anally, I can take a girthy 7.5" with relative ease. 8" tends to 'bottom out', which may or may not be the reaction that you are looking for.
I don't currently have a lot of experience with needles or humiliation / degradation, but that is something that I am looking to improve.