Moving to UK, what to do?

Depends on how long you will be there? Is this a short assignment or are you moving permanently.

If you're moving permanently I would recommend getting the transformer taps on your amplifier reconfigured for 220/240 VAC (assuming its a multi-voltage transformer). I say this because the performance of your amplifier will probably suffer if you use a step-down transformer instead of re-configuring, especially if its a high current unit. If you're using a step-down, pick a good one that weighs approximately the same as your amp and is rated 0.5KVA above your amp's rating. Your digital front-end and preamp don't suck too much power so you can plug these safely into the step down.

Sell everything and buy Linn and Tannoy replacements. Just kidding. Thought I'd stir the pot a bit this morning.

Step down transformers are cheap and easily available. In the UK you can try www.maplin.co.uk. You can buy a kilowatt step down transformer for less than 100 dollars.
The turntable might be the only tricky part, but check with all equipment manufacturers as some equipment detects the mains frequency and will not work if it is incorrect (e.g. Mark Levinson)

Overall I would not panic. I moved from the UK to the US a few years ago and changing country is a tricky business ... adapting the voltage on your hifi is the easy bit.

What is good in the PSaudiP300 that you can adjust the hertz, while all other converters give you 50herz

I moved from the States to Paris 2.5 years ago, and was faced with the same problem (110V gear running on 220V). Fortunately some of my equipment (Quad and Revox) is multi-voltage, no problem there. The rest is 110V equipment, Including two 200W/channel power amps. I simply purchased a 2kW 220V/110V line stabilizer transformer (~$200). You can purchase the equipment from www.eastwestintl.com or www.220voltappliances.com. The other thing to remember is, HiFi equipment in Europe, especially high end gear, is a lot more expensive then in the USA. Bottom line, bring your equipment with you and use a voltage stabilizer step down transformer to run it.

However, one thing to consider, and I learned the hard way. Certain US high end manufacturers (Krell for certain in the last ~10 years, and, I believe Martin Logan and others) put a frequency sensing chip on the power input circuit. This senses if you are running 60Hz (US) or 50 Hz (Europe) mains voltage (irrespective if it is transformed down from 240/220V to 110V and will not work if the power source is 50Hz. Krell in France charged me $180 to have my Krell HTS converted when I experienced this problem. Check before you leave!