I went back to England for mine and thoroughly enjoyed it. Had three different things - on the Saturday before (bday was on a Mon) I went out for a nice (posh!) meal with SO, parents and sister and bil, on the Sunday my sister did a birthday tea that the kids could be part of too, then on the day we did afternoon tea at a country house in the Lake District. I was spoilt rotten, it was very nice!
I'm not a party person and would have hated a big bash.

I also caught up with friends while I was over there who were turning 40 too, so it was nice to bemoan our age together.
3b in South Australia.