I've owned several S1's in the UK in recent years - my advice
1) Buy the very best aircraft you can afford (or)
2) Find a restoration based around a "sound" aeroplane with the right bits
3) "C of A" (most S1-T's or S2-S) single seaters are expensive to keep and have limited potential for revenue generation - Think £8k PA fixed costs
4) On a "permit", be ready for £2k insurance, £400 permit, 33l / hr 100ll fuel and inevitable maintenance costs (Like a £25k recover every 20 ish years) - Whatever you might think, you will be unlikley to fly more than 30 to 50 hrs a year or travel more than 100 miles from base.
5) The best UK S1's very rarely come onto the open market, they usually change hands by word of mouth
6) Lots of the stuff advertised in the 'States will not make the grade for the UK register - unless you REALLY know what you are doing it's pretty much a lottery, which very few "win"
Look at AFORS, the Baea website and flying club noticeboards, speak to Aerographic to register an interest (provided you're serious !)
Seriously consider a "share" as a first step (but you'll need to get some reputable training before most will allow you in)
The aircraft you mention is excellent, if you really want outright ownership and can afford it I'd say it's your best available option at present (and I'm nothing to do with it)
Good luck !