In my personal experience, the recruiters are friendly and receptive to professional interaction, so if you have relevant contact details, why not use them? We like to think airline recruitment processes are efficient, but sometimes it can be quite the opposite, and it’s easy for good, qualified Pilots to get missed/fall through the cracks. So don’t leave it to chance. If you already know someone in Jet 2 and/or have someone who sponsored your application, see if they can chase up for you, that worked for me!
Regarding the base choice. Jet2 will try their best endeavours to put everyone in their base of choice asap, and certainly one from the three choices that you give. The base transfer policy is very transparent once you join. If Airbus fleet/base is what you’ve requested, that may be a reason for delay, purely due to lack of aircraft, trainers meaning lack of available training sectors.
Without being too cheesy, one of our company values is ‘Take responsibility’, so why not give them a call or email? Nothing to lose IMHO.