Hi Claire
Hairdryer works well with 230v socket on mains hook-up depending on the ampage supplied. Most CC sites are 16A so a 2kw hair dryer is fine. In France on 6A hook-ups my 1200W hair dryer makes it - just. My DHG straighteners are 150W but 240V so can be used either with the inverter two pin whether or not on hook-up or the three pin socket when on hook up. I always use the three pin socket. Also worthy of note is that a lot of places that have hook-ups may also have toilets - shower rooms that will have a spare plug socket somewhere just for those appliances.
Slow cookers fine with three pin on hook up. Portable electric ovens, most are 800W so ok.
Charging laptops etc I have 12v chargers for everything. The 12V socket by the sink has a double USB adaptor fitted which is where I charge my I Phone and MiFi. The ashtray socket also has a double USB and that charges my I Pad and/or phone, I Pad Mini or whatever. The 12V by the bench seat - side door I use with my 12v laptop charger ( Apple macbook air) which I plonk in the rear seat pocket when travelling so it can be connected and charging whilst on the move.
The inverter socket I use almost exclusively for my Bose soundlnk. I have a 2 pin to uk three pin adaptor.
The rear 12v in the boot is what I use to power my 12v slow cooker when on the move. Nothing like a nice stew gurgling away in the boot whilst travelling!