Very impressive Lorenzo. Perhaps John West or Princes could sponsor your kit. The guy behind the net looks very tall, he should be playing basketball.
Welcome Karen, 3 in 4 months is nothing to worry about given your obvious endurance background. Glos may be a bit soon and Rome possibly not the fastest course so London may be your best bet although it's usually a bit hot by the end of April. As has been said, Berlin and Abingdon are fast autumn races.
As for big mileage weeks, everyone is different, but IMO 50-70mpw is probably quite unnecessary. There are several ladies posting here who are in the 3-3.20 mara bracket, interesting to see what mileage they do.
I have been wrestling with being competitive in ultras while trying to improve mara performance. It's extremely difficult to be your best at both and many talented ultra runners are rather average over 26.2. Deciding to focus on the mara time for a bit is undoubtedly the right decision. Good luck