These are definitely doable, particularly the 1.30 half.
For the marathon I’d suggest Advanced Marathoning by Pfitzinger - it starts with “up to 50 miles” which if you manage to follow that will definitely get you to 3.15 or lower.
I’m not a talented runner and my bests are 1.27 (20 years ago) and 3.24 (Paris 2015, following a too-light version of Pfitzinger.) Incidentally Paris is a beautiful marathon to do and easy to get into, but a bit late for this year.
A good read and I have a copy if you want to have a look.
Abingdon is a good local marathon to do and Tom C has run well there.
Very useful, thank you both.