Oh,I'm sure the Aussies will be quite at home !
I'm assured by people who have been to "the Old Dart" since last time I travelled in those parts(40 years ago),that the Brits have been dragged screaming into the 20th Century ( they haven't quite made to the 21st,but they are working on it).
Back in the day,if you were doing the tourist thing, it came to be about 3pm,& you felt like a beer ,you would find the pub was closed,so you had to find a shop somewhere to buy a room temperature bottle of "Tizer" to quench your thirst-- sticky, sickly sweet, & hot,not quite the same as a beer!
Fish & chip shops were good--when they were "frying",which was seldom!
Generally the "takeaway food" scene was abysmal--when Aussies,Kiwis & Yanks got together,we would whine about the food!

One exception,two really great pie shops in Southampton!
Having to drive 70 odd miles to London to buy KFC was a bit poor!(Probably served me right for living in a "provincial" city)
British Rail pies-----AAAARRRRRGGGGHHHH!
Strangest of all,one Sunday I was trying to buy some bath soap, as we had run out.
I went to a "corner shop" where they were amazed that I didn't know you had to buy soap at the "Ironmongers",which was really a hardware store!

I have been assured that all these issues have been addressed,& all is now sweetness & light.
But seriously,if they have enough time to get about & see all the "touristy" stuff,they will have a great time.
VK6ZGO