Location of flasher indicator relay on rover p6

look at this video
https://www.youtube.com/watch?v=OC8QlngoZh0
it is an earlier model car but your car may have the relay in the same horrible not easy to get at location.

I suggest you check with a repair manual or the dealer to ensure your car actually has a flasher relay - the flasher relay had been deleted from many of the GM Opel/Vauxhall range and replaced with a single black box that performs all the timing functions; flashers, wiper delay, interior lights, etc.

Many direction indicator faults can be caused by the hazard flasher switch, usually because of lack of use.

Check for relays and some bulbs, earthings.

Check fuse and flasher relay should be located in fuse box under dash

The location is shown in the owners' manual.

Most likely you have merely blown a fuse so check that first.
Next check the wiring to the trailer connection to see if anything has rubbed through to a bare wire

Not all relays are the same so you may have installed the wrong type.Consult the manual (get a copy of RAVE online) and/or contact one of the reputable parts suppliers stating your model and VIN - that will ensure you get the correct replacement

Indicator Flasher The turn signals and the hazard warning flasher switch (13A350) use the same indicator flasher (13350). The indicator flasher is located behind the instrument panel (04320), to the right of the interior fuse junction panel. When activated, the indicator flasher flashes the appropriate turn signal lamps.

Removal

1. Disconnect the battery ground cable (14301).
   

1. Press the indicator flasher tab and slide the indicator flasher from the mounting bracket.
   

1. Disconnect the indicator flasher electrical connector from the wiring harness.
   

The relay is  located on the wiper/indicator stalk assembly behind the steering column cowling. It should be on the opposite side to the ignition lock.

Have you checked the flasher relay. It should make a ticking noise when using the indicators or hazard lights.
This could be your problem
good luck

find location of indicators/flasher relay h/book will indicate which relay or look at fuse box/relays cover underside ? it may have diagram? try another relay? and ensure contacts are clean where relay plugs in