FWIW now that you have bought the tool kit. As John said, it contains a lock for the injection pump pulley. It is the large round disc with a lip on it. First you screw the crank lock into the bottom of the bell housing wade pug hole. Turn the engine to tdc and it will lock. You remove the three bolt timing cover plate, undo the three 10mm head bolts, and bolt on the clamping ring. Then you can remove the nut on the end of the injection pump shaft and pull the pump only out, leaving the belt pulley engaged in the belt. This preserves cam belt timing and is the way the job is supposed to be done. Ie no need to open the front of the engine, drain coolant etc. Changing the pump this way takes about an hour.
If on the fence, Blue Ridge Diesel Injection Service here in Salem Va have done dozens for Robert Davis and I. They are a Bosch service center. Cost to rebuild using the latest low sulpher tolerant seals and o rings is around $600. Elton Wright there is point of contact, knows Tdi's, he drives an immaculate 200 tdi powered 109. This avoids the international shipping scenario and they are top notch and turn things quickly. You can find cheaper remans possibly but they were likely done in a sweat shop with who knows what quality rebuild kit and are only being retailed by the large company offering them on the internet.
FWIW, the last pump I took them was because it was leaking, turns out that pom Nigel had over tightened the tensioner and put too much tension
on the IP shaft and worn out the bushings in the case that the shaft rides in. Don't over tighten your belts boys.