Keep meticulous records of what is received when. Gifts that are given regularly like £100 birthday and christmas cheques or even a regular contribution to e.g. music lessons is just counted as normal spending and will not incur inheritance tax if they come out of GPs discretionary spending from their monthly income and aren't reducing their capital assets. Gifts that couldn't be repeated regularly, which deplete their assets and will reduce their income henceforth, are only liable if GPs die before 7 years after the gift, pro rata. So if GPs give £70,000 one-off gift in 2025 and then survive until 2030 and die then, £50,000 is iht free. The recipient of the £70,000 almost certainly doesn't pay anything though - the IHT valuation on the whole estate is increased by £20,000. If the remaining estate is already over the iht threshold then that will mean the IHT bill is increased by a further £8,000, paid by the estate before the Will is executed. If the remaining estate is £20,000 or more under the iht threshold there is no tax to pay, and if it was a little under but the £20,000 addition just tipped it over the threshold, iht is only due on the amount over the threshold- but in any case it is the estate that pays, not a living person.
The only circumstances under which a living person might theoretically have to pay anything would be if the amount they give away is so extreme, and the duration after such gifts that they survive is so short, that the IHT bill after adding the pro-rata amounts of recent gifts to the valuation of the estate makes the IHT due be greater than the remaining ungifted assets. So if they start off with assets of £2,000,000 (which if they died with no gifting would incur IHT of £470,000 leaving £1.53m to distribute according to the Will) and they give away every penny of assets except for a small flat they live in worth £350,000 and not a penny of other assets but die only a year after doing so, then the IHT bill is £403,000 and only £350,000 of that can come from the estate so the recipients of the £1.65m that they gave away would have to cough up the remaining £52k due. This is an extremely unlikely scenario.