Although the 57s benefit from a low powered amp, they will be revealing of its inadequacies in the mid-range. When I got my first pair back in the early 70s, I used them temporarily with a Dyna Stereo 70, then a ubititous, cheap tube amp. I later used ARC tube amps in the 60-75 watt category- those were sweet in their day- but you don't really want to zap the speakers.
I would assume that in the UK, you have access to some interesting older products- I suspect Quad IIs are somewhat pricey, because of their collectability, but I don't know the market. Not sure, but I would also suspect Sugden make something low powered that is enjoyable to listen to; your ears will get better once you have owned 57's for a while, so the cheap throwaway amp may be no bargain if you get a hankering to hear what the speakers are capable of revealing.
I would assume that in the UK, you have access to some interesting older products- I suspect Quad IIs are somewhat pricey, because of their collectability, but I don't know the market. Not sure, but I would also suspect Sugden make something low powered that is enjoyable to listen to; your ears will get better once you have owned 57's for a while, so the cheap throwaway amp may be no bargain if you get a hankering to hear what the speakers are capable of revealing.