As others have said, if you have one of those split face plates, then you can legally remove the lower half and wire to the back of it. That part of the plate actually plugs into the master socket - and that satisfies the "must be plugged in" requirement.
Ideally, get an ADSL filter that fits in place of the standard plate - this splits the ADSL from the internal wiring as far upstream as is practical and gives best results (speed) on your ADSL. However, many of these only have terminals on the back for the phone line - you want one with an extra pair of terminals for the ADSL. If you get one of these, then I'd suggest you wire it as follows :
Wire the Blue pair to the (filtered) phone line terminals - blue to 2, white/blue to 5. You should probably also connect the Orange to 3, but I don't think many phones actually use the ring line these days.
Connect the Green pair to the ADSL terminals (possibly labelled A&B as they connect direct to the unfiltered phone line).
If you can't find a filter with terminals for the unfiltered line, then you could bring out the Green pair and fit an RJ11 plug to go in the front of the plate, although it doesn't look as neat. What you aren't allowed to do is wire the Green pair directly to the A&B terminals on the back of the socket - though I suspect an awful lot are.
At the other end, connect the green pair to one socket for the ADSL modem. Just connect it direct, you don't need a filter.
Connect the Blue pair (and Orange) to as many sockets as you think you are likely to need. When using Krone punchdowns, if you turn off the cutter in the tool it's usually not hard to keep the wire intact and you can daisy chain it along several sockets without joins fairly easily. You can then patch the phone line to outlets as required.