A note on tyres.
It is true to say that good tyres will improve a disco's offroad ability.
It is also true that tyres fitted as standard to all but the earliest discos reduce their ability.
ie, it's as much about fitting tyres the vehicle SHOULD have been fitted with as standard as fitting upgrade tyres...
Don't believe me? look at what the last of the line TD5s were fitted with in contrast to what the early G***WUD and G***WAC 3 dr discoveries were fitted with.
What's my point? well despite the fact that the vast majority of standard discos having comically inappropriate tyres fitted they are still astonishingly capable offroad. You need to try it as standard and get to the point where you are regularly getting stuck BEFORE you do any modifications so that you have a benchmark to work from.
It is very easy to want to go for the most capable offroad tyre you can afford but remember that everything is a compromise,yes INSA ST are incredibly capable offroad, but they're ****e onroad when compared to an AT tyre, fine if you're building an offroad challenge vehicle, but bloody annoying if you want to use the disco as the talented multi purpose vehicle it is. (because they're noisy and reduce onroad grip) What else can follow a defender into the wilderness in the day yet take 5 adults and 2 kids to a fancy restaurant in comfort in the evening?
Also bear in mind that lifting a vehicle is usually done for 3 reasons and imo in order of importance :-
To allow the fitment of larger tyres ( gives more clearance under the diff)
To allow greater axle articulation ( with suitable extended dampers, brake lines etc)
To look good
You're only up the road from me (hucknall) so you're welcome to pop over to my workshop and ill show you what I've done to mine and why I've done it...