Can you advise whether it's OK to use push fit fittings on 15mm copper pipe behind plasterboard and tiles when fitting a thermostatic bar shower please ? I'm using a https://www.screwfix.com/p/cassellie-easy-fix-bar-valve-wall-mount-fixing-kit-chrome/689hf to fit the shower so not use if I'd need to use Yorkshire soldered fittings instead. Thanks
Those shower fixings are cheap for a reason ... they're utter carp! You only want to do this once, right? If so, then spend a bit more and buy something that, ideally, is soldered. If you don't want to, or can't, solder, then use one with compression fittings. Also get one in which the pipes' spacing is fixed at 150mm centres. The manufacturers of these things will do a far better job of spacing that 150mm accurately that you could ever do yourself ... and that'll become increasingly important when you try to fit your shower bar.
Yes, you're ok to use push fits on copper pipe within a stud wall. Have never used those fixings kits that claim to 'auto shut off' when the shower valve is removed, they may work well, but I'm not convinced. I normally use the standard sort like these https://www.screwfix.com/p/swirl-bar-valve-wall-mount-fixing-kit-chrome/8669h. Although many shower manufacturers now supply their own with the shower, which is nice.
Thanks for the replies Yes, I'd agree re the auto shut off. I've fitted isolation valves further back on the pipework and am intending to install the fitting but leave out the auto shut off parts.