Using Australian Appliances in Europe

Europe is all 220-240V, so no voltage conversion is required. There are many types of socket outlets in use across Europe, so you'll have to be more specific about what you mean by "high wattages" and which country. UK standard outlets are

13A (3kW) max per outlet. France, Belgium and countries which use the Shucko outlet are 16A (3.5kW) max per outlet. Other european countries have various slightly lower limits.

Also note you will need a good quality adaptor for high power appliances. Something that was really designed for just a shaver and doesn't meet any of the national standards is not going to be suitable. You could bring a high quality Australian short multi-way socket block with you, and buy a proper replacement plug locally on your arrival. Also note that whilst I believe the Australian supply is polarised (it has a defined live and neutral), most of Europe (except the UK) is unpolarised at the socket outlet. This means your Australian appliances may end up switching the neutral, or running from a supply where neither main conductor is a neutral, which may not be what they were designed for.

Although Aus oulets are polarized by design it is easy to get them reversed with amature made extension cords etc and I have never heard of it being a problem.

Perhaps in theory a device with a switch could pose a problem if it was opened but unless a device is approved Double Insulated it would be grounded and as in UK the ground is tied to the neutral at the building entry point. Wall switches are tested (we hope) at installation time and all power outlets have switches unlike the UK which (correct me if I am wrong) has some outlets with shutters but no switch.

Aus devices are mostly limited to 10amps with the common plug or specials with a modified plug and special outlet can be 15 amps.