A Thatcher Library, in the form of those US (ex) Presidential libraries, will no doubt be a good thing. American Presidential libraries are actually public libraries, administered at taxpayers' expense by the National Archive and Records Administration (NARA) under the Presidential Records Act. We don't have such provision in the UK, so Margaret's would have to be privately funded. And perhaps this is more suitable, under the circumstances. Part archive, part museum I would expect permanent exhibitions on both the Berlin Wall and the Falklands. And just as the Reagan Library sells copies of the famous RR Stetson at $209.95, the Thatcher Library could vend tasteful copies by Mulberry of those handbags at a similar price point. Or the 'Thatcher Steampunk tank Pashmina and goggles' perhaps.
Of course no Thatcher venture would be complete without some hideous embarrassment caused by her wayward son, so we'd have to expect a concession stand run by Sir Mark offering gay men's underwear with 'Thatcher' embroidered on the waistband and no doubt these will prove popular also with the gangsta types who wear their jeans half way down their bottoms.