once you requested the landing you only have 10 min to get to your ship(the green dot on your sensorpanel) remember you wont be able to "see" your ship as its parked beneith the landingpad. just drive into the "celler-bay" where the green dot is and stop once the little blue dot which indicate "ready to board ship" lits up. then choose the same panel as you used to deploy the SRV, to now "Board ship"
you can also just destroy your SRV but that might cost you the mission if at any, and the cost of a new SRV...
And finally there is the third options(might be an exploits in FD's eyes) you simply exit the game, and log back in, but this time in Elite Dangerous(NOT horizon) and you will automaticly be in your ship hoovering above the planet you were on....