Neil Kinnock will probably only win in 1992 with a small majority, perhaps even smaller than the OTL one that John Major gained. Major probably loses the Conservative leadership thereafter, though, remember, the Major of 1992 is a lot more popular than the Major of, say, 1994, with his backbenchers, so if the defeat's only a minor one, there's a chance he could stay on as Leader of the Opposition. Otherwise, the leadership's likely to go to Heseltine. Norman Lamont could also concievably grab it, but I think Heseltine's the more likely option.
Black Wednesday will be a disaster for Labour, probably, though, if they're still enjoying something of a honeymoon, it's possible they can still turn round and blame it on the Tories. Nonetheless, it's not going to do anything good for the Labour Government's polling figures. Economic recovery will come after Britain's out of the ERM, but (partisan alert!) I suspect that the higher taxation brought in by a Kinnock Government will slow it somewhat.
Both parties will probably become more Eurosceptic, prompted by Labour's experience of dealing with the EEC, and the influence of Conservative backbenchers upon their leadership. Were Labour for, or against the Maastricht treaty? This could have some interesting butterflies.
A Tory defeat in 1992, could, paradoxically mean George HW Bush is re-elected later that year, given a lot of his campaign intelligence came from Conservative Party officials. With the Tories going into Opposition in the summer of 1992, a lot of these advisers will be discharged, and it seems reasonable they'd try to get involved in Republican Party politics. A mid 1990s Labour Government, and a Republican Presidency until 1997 certainly strangles any ideas of New Labour at birth.
British Rail survives in some form, or, at least, has a stay of execution. The Tories may very well propose privatisation in their 1996/97 manifesto.
I'd expect the Conservatives to be returned to office with a decent majority in 1996 or 1997, though that could be partisanship speaking. In foreign affairs, the EU will have developed differently, and the dissolution of Yugoslavia certainly would be altered. Assuming HW wins the '92 Presidential Election, who do the Democrats nominate in 1996? After sixteen years of Republican rule, the White House is presumably their's for the taking...
And, lastly, I believe Britain would've been a much, much better place had Labour won in 1992. You'd probably see distinctly ideological parties, for one thing, as opposed to all striving for the centre. The whole lack of trust that started under Major and blossomed under Blair is butterflied, though I suppose it's possible it could've happened under Kinnock too.
Basically, I reckon the 1992 Conservative victory was a bad thing for both the Labour and Conservative parties, and its impact on both of them is, now, nearly twenty years on, only just beginning to be fully felt.