Is there much work involved in the removal of the valve to clean it?
Can you recommend a good carb cleaner that would be useful?
To stop the valve from clogging up again, is a blanking plate of any advantage to the running performance of the car?
Yes, a solid blanking plate will prevent the build up of soot from you EGR valve, your TDDI is a euro3 so you can blank the EGR with no problems - you can get them online for about £5
Super-dooper cleaner is a waste of time & money, as is cleaning the EGR valve with spray (the effect/ benifit is limited), just fit the blanking plate. If you really want to clean the "system" out, you should completely remove the EGR valve, inlet manifold and associated components from the car and clean it properly
You could fit a crankcase breather catchtank to your breather hose, any oil vapor/ spray from your crancase would be "caught" instead of going into your inlet
your crankase may have become pressurised from the turbo via the bores, valve guides or seals, or the head gasket (thus throwing out the oil) this is not good, but the breather catchtank may be enough to keep the car going, avoiding costly repairs
PS - you should never let the oil drop below the min. level on the dipstick - if you top it up to full (to give it a longer time before it goes down) or halfway (because it may drink less oil than full) and keep checking it, you could keep oil in the car, you can use the cheapest (new) oil you can find, oil can get expensive if you are using a lot of it, its ok if its 20-40w in the summer, 4 or 5 liter tubs can be very cheap in thritht stores etc - its not "perfect" but better than letting the oil run dry, new 20-40w is better than old 10-30w, anyway