The UK hasn't put all its eggs into one basket at all, they've pre-ordered literally hundreds of millions of vaccine doses from, I believe, 6 or 7 different candidates, encompassing all types of vaccine development. I don't foresee that any country is going to vaccinate all its population with just one type of vaccine anyway, especially in the short to medium term.
Was talking to a friend who works in biotech and he was slightly less bullish about some of the data, in particular the current lack of data about whether the vaccines actually stops infection totally (as opposed to stopping serious infections, which of course is still an amazing win) and subsequently, whether this actually would reduce community transmission from an asymptomatic carrier from their upper respiratory tract. Not quite as much of an issue in a situation where there's widespread vaccine uptake but that won't be the case immediately of course and also we have the issue with anti-vaxxers.
Also, this will sound silly but the pfizer vaccine is apparently quite painful ( I haven't seen the data yet). This might sound like a silly point (and for most of us on here, it would be) but with an increasingly vaccine skeptic population, 2 painful jabs a month apart...may mean that some people don't turn up for their 2nd jab.
We'll see. Perhaps long term, an intranasal vaccine or something may be the best but there's a lot of good news for the short term anyway.