The answer depends on whether your mate is thinking about bringing it over to keep or bringing it to sell.
If they want to run a big 4x4 here I would think about bringing it over. They'll probably not find another 105 in the UK, and good Landcruisers don't seem to be that easy to find these days.
If they're thinking about bringing it over to sell though, I would say it's worth more in Aus than here. Especially after you factor in the cost of shipping, registering, etc.
As for a value it's hard to say. Don't know if Toyota ever sold the 105 in the UK, so not much to compare it against. I don't know if it would go for more than £10k though, and if they get the advertised price in Aus they'll be £3k in front without the cost and hassle of shipping and importing.