From PANS-OPS Doc 8168
"........ Normally, a racetrack procedure is used when aircraft arrive overhead the fix from various directions. In these cases, aircraft are expected to enter the procedure in a manner comparable to that prescribed for holding procedure entry with the following considerations:
a) Offset entry from sector 2 shall limit the time on the 30 deg offset track to 1 min 30 secs after which the pilot is expected to turn to a heading parallel to the outbound track for the remainder of the outbound time. If the outbound time is only 1 min, the time on the 30 deg offset shall be 1 min also.
b) Parallel entry shall not return directly to the facility without first intercepting the inbound track when proceeding to the final segment of the approach procedure.
c) All manoeuvring shall be done in so far as possible on the manoeuvring side of the inbound track......."
Thus, for the Calais approach, if your heading to the MK was between 179 deg and 237 deg, the join for the racetrack would be a Sector 3 (Direct) join. If the heading was between 069 deg and 167 deg, the join would be Sector 1 (Parallel). A heading on or between 168 deg and 178 deg means you can choose between either a Sector 1 or 3 join.
The vertical profile I would adopt is that suggested by Chilli Monster. Bookworm's interpretation seems to cover entry to the racetrack but not the rest of it. If you assume that the descent to Alt 1310' cannot take place until you are within a half-scale deflection of the localiser, this would mean that you would have to be on the 242 QDM which would probably place you very close to the MK and certainly within 6.1 DME thus placing you above the glideslope. Following Chilli Monster's suggestion means that your right turn from the outbound track (063) to the inbound track (243) takes place further from the beacon enabling you to start the descent earlier. That said, I would start the descent at 6.1 DME and not before (assuming my DME was serviceable).
I could be wrong, of course.