I agree with Mad Hat Man.
A set of AT tyres and you are away on the slippery stuff.
The underbody protection (try Celtic 4x4 for ideas) doesn't improve your off roading capability but provides much needed peace of mind. I've had Defender officonadoes in the Freebie when there's been a bick clunk or scrape and they look at me expecting the thing to fall apart - nah, just the underbodyprotection doing its thang ... It's not too radical a modification, because it's generally bolted on to replace the factory spec engine sump protector, or added on to protect the fuel tank/exhaust. Sill guards might be an idea if you are worried about dents.
Having a lift is pretty much the most radical thing on the list. A two inch lift gives you the same clearance as a showroom-spec Defender.
Persoanlly, I think the best thing to do is get out there and have fun. Don't let anyone tell you the Freelander isn't capable off road - it is suprisingly capable. What you do need to get a grip on at an early stage is its limitations. Often, off road problems can be dealth with a little parrallel thinking. Otherwise, know what your approach and departure angles are, because often you can't reverse out of what you have driven into, especially with the lack of low ratio to give you more control when reversing up an incline.
To illustrate the capability of the Freebie, I went to a play day last year to try out the winch, which I had never had an oppurtunity to use and didn't want to use for the first time in anger.
It was a site I know well, and have visited before but always stayed clear of anything that I wasn't reasonably sure the Freebie could get me out the other end of. It was very strange, actually going into sections that I wasn't expecting to get out of under my own steam ... and two of the four obstacles, the Freelander just ate up and spat out ... and to think that I had always steered clear of them before!
Came home very muddy, quite tired but full of respect for a very plucky vehicle.
Cheers
Blippie