He famously admired her.  For example, in a letter to Robert Conquest (29 June 1981) he wrote:

“… La divine Thatcher is planning to slim the universities. None is to be closed (shame!) but seemingly we are to be told what we had better pack up (Applied vandalism, Theory and practice of Treason, Protestology etc.) …”

In another letter to Robert Conquest (23 Dec 1984) he wrote;

“… Well we now have Ted [Hughes] as [poet] laureate, [Larkin had turned it down], as I expect you’ve seen.  Mrs. T was very nice about my not wanting it. What a superb creature she is – right and beautiful – few prime ministers are either. …”

On the only occasion he met her, he was pleased that she had not only read one of his poems but also remembered enough to misquote it.  In a letter to Julian Barnes 27 Sep 1985 he wrote:

“… Your anecdote reminds me of a brief exchange I once had with Mrs. T., who told me she liked my wonderful poem about a girl.  My face must have expressed incomprehension. “You know” she said. “Her mind is full of knives.”  I took that as a great compliment – I thought if it weren’t spontaneous she’d have got it right – but I’m a child in these things.  I also thought that she might think a mind full of knives rather along her own lines, not that I don’t kiss the ground on which she walks. "

The poem was Deceptions.  How interesting that Mrs. T. should have read and remembered this nuanced poem about rape.  Read it here.

"She has a pretty face, hasn't she, I expect she's pretty tough." Letter to Eva, his mother on 12 Feb 1975.

"Her great virtue is saying that two and two makes four, which is as unpopular nowadays as it has always been."  Interview with Graham Lord, 8 August 1979: 

"I adore Mrs. Thatcher. At last politics makes sense to me, which it hasn't done since Stafford Cripps (I was very fond of him too). Recognising that if you haven't got the money for something you can't have it - this is a concept that's vanished for many years."  Required Writing: miscellaneous pieces. Faber 1983.