Given your times last year I'm sure you'll be good for the sub 2 hr 50. I got a 1'58" last year on our rolly course on 53x15. Two days later I mullered my 25 PB on the same course which sadly brought the realisation that I hadn't been training hard enough.
A couple of targets for me:
an 18 on the UC251 (8.3 Miles) - best last year was 19.13
a 21 on the U7b (10M)
a 20 10M
sub 55 for 25M
Not sure I will have time for anything longer than a 25 (apart from maybe some hardriders) but maybe a sub 2hr 50.
On a related note - our clubs "Mega-Hilly" TT isn't on this year, any suggestions for a VERY hilly TT?