You can give away as much as you like. Simply make sure that you don't die within 7 years of doing so!
If you die within 7 years of making monetary (or other) gifts, the value of those gifts (or part of that value, depending upon the period which has elapsed since the gift was made) can be taken into account when assessing whether your estate is liable for Inheritance Tax. If the value of your estate would come to less than £325,000 (using the current threshold) anyway, there would be no IHT to pay.
Further, you can give away a TOTAL of up to £3,000 per year without that amount being included in any assessment for IHT. If you don't use the full allowance in any year, the residue of that allowance can be added to what you're allowed to give a away, free of IHT considerations, in the following year (but only for that year - you can't transfer it forward beyond then).
http://www.hmrc.gov.u...ey-property/index.htm
Chris