Many employers have a checklist of skills, and the job applicant is to self-rate her/himself for competency in each skill -- for example, starting IVs, drawing blood, assessments (which includes auscultating lungs/heart sounds), inserting foleys or NG tubes, wound care, drug calculations/administration, drain management, therapeutic communication, etc...
As for auscultation, a med-surg nurse really only needs basic skills. I would know these things beforehand, for they are assumed knowledge & not really part of orientation (ie. all students do it in nursing school over here). Make sure you know where to listen for the heart sounds, but don't worry about s3/s4 sounds or locating murmurs (the regular "lub dub" heard are the s1/s2 sounds); as for lungs, just know how to distinguish "clear" sounds from diminished or coarse sounds, and what crackles sound like -- if you know these things, you'll be fine on the job; crackles can indicate fluid or other things, as can diminished lung sounds. Of course you need to be able to id wheezes too, but often the pt looks like they're in distress or they're audible without a stethoscope; in this case, a pt may need a nebulizer treatment or to deep breathe and cough. Look in a textbook for diagrams of where you place the stethoscope on the body to hear the heart or lungs. For the heart, I usually listen to the left of the sternal border or the heart's apex. You can detect artificial heart sounds (a "click") with implanted valves. For the lungs, it's often adequate to just listen to the top lobes (front/back) & bases (also front/back). It often helps to have a pt take deeper breaths through their mouth while you auscultate, to make the breath sounds louder & more distinguishable. Finally, you count the heartbeats as you're auscultating for 60 seconds & notice if the rhythm is "regular" or "irregular" (or you can palpate the arterial pulse, count for 15 seconds & multiply times 4). As for lung sounds, you can listen for only a few seconds in each field; when you count respirations, do it without auscultation for 15 seconds & multiply by 4 for the breaths/minute.
You'll need to auscultate the abdomen as well, for the absence of bowel sounds can indicate an ileus (also, sometimes they're absent after any routine surgery & a pt will become nauseated & throw up if they eat before the sounds return, indicating that the GI tract is still "asleep" from anesthesia). Just use the bell of the stethoscope & hold it lightly over the abdomen, and listen to the four quadrants around the umbilicus; the sounds can be very subtle, like "tinkles" or "gurgles"; in order to determine that bowel sounds are "absent", you must listen to a full five minutes -- this is b/c the diagnosis of absent bowel sounds can indicate something very serious. If you notice the abdomen is firm & without sounds, call the doc immediately if this is an unexpected finding!
By the way, what technical skills are regularly performed by UK nurses? Just wondering, for I've always dreamed of working overseas.