This question came up in my game a while back and I engineered some concepts that might not be completely canon might be functional.

Planetary Interaction:
- Planet Landing is restricted to Transports, Raiders, and Frigates
- Landing Ships are restricted to land at Space Ports that have at least an established Low Port
- Landing method is based on the mass of the ship, for each 5 Megatons of ship the ship needs 1 system ship tug to lead it into the planet landing zone
- The landing zones are specifically designed to support a specific amount of mass per square kilometer landing zone
- The landing zone platforms are Hive Structure style crawlers that transfer the ship into linear catapult style system that slowly starts accelerating around the world in question until they reach high orbit were the ship is released and allowed to move on its own power and when they leave orbit they activate the main engine.

The Planetary Tugs:
This are specialized Mechanicum System Monitors that have a rough mass of 5 Megatons that have oversized engines that can handle up to twice their mass and have supplemental thrusters to move in the atmosphere.

Player Owned Star Ports:

Star Port Charter
- Compact with Forge World
- Good Reputation with Mechanicum
- Ownership of location for Port

Star Port Core
- 20 Profit Factor sink
- 12 Structure Slots
- Benefit: +100 AP Trade Endevours

Star Port Power Station
- 5 Profit Factor sink
- (-1) Structure Slots
- Benefit: +5 Megatons Launch Capacity to MagLev Launch System

Star Port Landing Zone
- 1 Profit Factor Sink / Megaton a Landing Zone can support
- (-1) Structure Slots for Transports, (-2) Structure Slots for Raiders, (-3) Structure Slots for Frigates
- Benefit: Ability to land (1) ship of the specified ship class

Star Port MagLev Launch Facility
- 5 Profit Factor Sink
- (-1) Structure Slots
- Benefit: Ability to Launch (1) ship into High Orbit of the planet

Star Port MagLev Communication Uplink
- 5 Profit Factor Sink
- (-1) Structure Slots
- Benefit: Ability to Launch and Land (1) additional ship per month

Star Port MagLev Communication Nexus
- 20 Profit Factor Sink
- (-2) Structure Slots
- Benefit: Ability to Launch and Land (4) additional ships per month

this are just some of the things I worked with my players that you guys might be able to use.

I rather like this list. It also hearkens back to my thread regarding lifting bigger ships off of a planetary surface. I always found it odd that the book has the Planetbound for Millennia background (Into the Storm, I think), and numerous ships in several books, but none had a ship like the Tug, something that could haul a big wreck back up into space, or tow a station/station component through the Warp, to get it where it will be established. It made me sad, because if I were to find something worth salvaging, and wanted to get it, I'd have to make something up, when they had given so many other things to me.

As for landing ships on the planet, I'd say, overall it's not for Imperial ships. The scale of Imperium ships, compared to numerous other series, like Star Wars, is HUGE, and such bulky things would never get off the ground again. They would need support mechanisms of their own, to say nothing of the place they would land needing to be reinforced, and the area around it would be decimated by its efforts to take off, again. These ships are even built in space, for the most part, meaning they really weren't probably designed to need to escape gravity; they never have before. For your group to go down, a landing shuttle of a thing, or maybe a troop transporter would be necessary, or shell out the extra points for a teleportarium, if it can fit with your ship. Transports might be my cutoff point, as they are as their name implies, designed to move people or goods to other locales, but bigger ships should stay where they were born, and meant to live and die; the Void.

 point taken and I agree but if the players want to land the ship well this are the guidelines and seems a happy medium of techno black box tech and narrative style gaming. Besides they have to pay for the privilege of landing the ship in the first place and making suh a heavy investment in the planetary infrastructure makes them bound to the location.