Looking for a 5/6/7 a side game of football

Hi all. Relatively new to Portsmouth and keen to get back into playing football in the evenings.

Any suggestions on the best way to get a game? Looking for a casual/friendly kick about match (turn up, choose sides etc.) rather than joining a team in a league.

Am 38, decent fitness, solid 5 a sider - nothing flashy but not also not going to ruin a match by being terrible.

Any ideas, offers, apps etc. very welcome.

Thanks!