Funny you should ask but i am studying this at the moment on my way to becoming a solicitor so here are a few points that may be of some use:
1. Under current tax rates the first £300,000 of his estate will be exempt from tax (nil rate band). This figure will increase in the next financial year i forget how much to but i can look it up if you like. Gordon Brown set down the nil rate bands for the next few years already and the rate that is in effect when your uncle dies will apply.
2. If you make a gift to a person in your lifetime then it is exempt from inheritance tax if you survive for 7 years after the gift.
3. Everyone can make gifts using their annual exemption of up to £3,000 each tax year which will not be subject to inheritance / capital gains tax. If you have not used up the previous years annual exemption then you can use this too - so the maximum gift would be £6,000 this year if last years was not used and £3,000 for each year thereafter.
4. You can also make a gift 'in contemplation of marriage' which can also be tax exempt - I forget how much of the top of my head.
He might want to consider setting up a trust which could help avoid some tax but i'm not going to go there as i will fry your brain and mine as its way 2 late on friday for trust talk.
A simple thing i would suggest is him using his annual exemption each year to reduce his estate and thereby avoid the tax man getting his hands on 40% of the estate above the nil rate band (currently £300,000).
Be careful if he decides to sell off some assets as the disposals may attract capital gains tax.
These are just a couple of things off the top of my head which i hope helps but I would def advise independent legal advice to see if there are any more exeptions you can make use of.
Wow and i thought this information would never be of any use to me!!!
Hope this helps, any queries let me know and i will do my best to clarify.
Deano