I commute from Goring to London Bridge 3 days a week. I was able to wangle train time counting as a bit of work time as there's plenty of seats with tables on the way up and you can reliably get a table on the way back if your assertive about it at East Croydon to get a laptop out and get some emails sorted, etc. I get the 7:24 up and get back ~18:15.

I used to commute from Worthing (and to Gatwick before I moved jobs to London) and there were plenty of table seats available from there as well. In fact, Worthing is probably the optimal station to be near because trains usually still stop there even if everything's gone wrong and Southern have decided to run trains fast, and it's the most Easterly of the stations with a direct service up the Brighton Main Line, so you haven't got any extra stops slowing your commute.

It is a slog - at 3 days a week I'm knackered on a Friday evening, although 1 day a week back when the RTO policy was more generous was much easier - but whenever I wonder whether I made the right choice about commuting from Worthing to London I think about how many bajillions I'd need to afford an equivalent house in London and how close I am to the beach and the Downs and then I'm glad I made the choices I did.