Hi Mick,
Yep welcome to Land Rovers...Lol
Common problem, it will just be a very slow drip, it will strip all the paint off in the foot well (where ever it spreads too) but if you keep an eye on it you can drive it for a long time. But master cylinder will need to be replaced.
Not hard to do, couple of hours from start to finish, worse part is bleeding brakes. A one man job except bleeding the brakes unless you can suck it through.
You will need to remove the fluid reservoir (which means bleeding the clutch as well) and the bracket holding the "jam"tin, six bolts in the foot well holding the assembly in place (captured nuts so easy to undo) and remove the brake pedal etc, then swap over the master cylinder, try and remember the position of the adjusting nut and put it back in the same spot (you'll see what I mean) it make it easier to get a good brake pedal feel when bleeding up again.
Give me a call if want any more help
Pretty sure Dennis M has a post about this in one of his threads, I'll have a look.
Check this out and get some motivation!
http://www.aulro.com/afvb/leaf-sprung-military-land-rovers/111187-113-372-a-44.htmlcheers
Scott