Thinking about an au pair. Could anyone share tips and experiences please?

No idea. We live in the party district of a big city!
My younger cousin is however on aupairworld looking for a family. She seeks a town (not big city) with hills for walking, a local pool, access to a car and ideally pets in the home. All sorts on there.
Make sure you interview and are as straight bat as possible with candidates.

Definitely second the weeding out of non-social candidates, and a tour of all that your local area has to offer in term of events, classes, meet-ups etc

To avoid the horror of an au pair hanging around every evening and weekend we sort of interview out those that don't seem social. We often end up with ultra social party girls but that's fine, I'm happy for them to be out partying as long as it's not the night before they work. We invite them along to most events but within a month or so of joining they tend to have busy social
lives of their own. They do eat with us each night though. We like that.

We have had au pairs for five years. They have changed my life. It takes a village to raise a child, or so the saying goes, I have bought my village in the form or au pairs. We hire through au pair world for the academic year only. We always choose girls on a gap year because I like them young so I can mound them. I also find living with teens fun.

All our au pairs have been like family. We keep in touch with them all and they visit regularly. They have all loved our children and our children have adored them.

Living with an au pair is easier than we feared. In fact having another "adult" around means DH and I step-up, we cook nice meals and chat about our days over dinner rather than slouching on the sofa.

The flexibility of 25 hours a week care plus two inclusive babysittings is a lifesaver. DH and I go out to the cinema and all sorts. Things we would never have paid a babysitter for.

Scoutism?

Sorry no idea on how to spell this.

Anyhow - we actually went through thorough interview process 2nd and 3rd time round.

We used an agency first time. Waste of money, and they were useless when we sought help. First au pair was in hindsight too young, it felt like having a third child although she was lovely with DDs. I found it very difficult with her expectations to share every moment in our life including WE and holidays (which we took her on and she came along, sulking quite a lot like a teen). Altogether, she failed to provide much outside of after school care for DD1. And refused to go out / visit on her own.

Our next two were through aupairworld. Lovely girls, a bit older, with specific qualifications in childcare or scouting from my home country. They actually quickly made friends in our city and developed their own network of friends and activity. Both used to go party most evenings and WE once done with their duties. Some minor niggles with whether or not they do need feeding at WE etc. Took them on hols when we went. They were friendly and professional.

That was meant to be "hmm" not "mum".

Mum. Been there, done that - 3 years altogether.
We started when DD2 was tiny and DD1 started reception, mostly as a flexible solution to childcare DD1 mainly afterschool and for DD2 (in full time nursery)

I found out a lot. For example: I am not as flexible as I thought, nor as "young" as I thought. And I really like walking around during naked in my own home, which I obviously could not do anymore.

We have now gone back to childminder in the afternoon after school and do the mornings on our own. Got easier as DD2 grew older, and am very happy to go around naked as I used to!